diff --git a/core/rawdb/accessors_indexes_test.go b/core/rawdb/accessors_indexes_test.go
index a812fefeaa..926c92ba8f 100644
--- a/core/rawdb/accessors_indexes_test.go
+++ b/core/rawdb/accessors_indexes_test.go
@@ -297,3 +297,61 @@ func TestExtractReceiptFields(t *testing.T) {
 		}
 	}
 }
+
+func TestSenderNonceIndex(t *testing.T) {
+	db := NewMemoryDatabase()
+
+	addr1 := common.HexToAddress("0x1111111111111111111111111111111111111111")
+	addr2 := common.HexToAddress("0x2222222222222222222222222222222222222222")
+
+	txHash1 := common.HexToHash("0xaaaa") // Sender: addr1, Nonce: 1
+	txHash2 := common.HexToHash("0xbbbb") // Sender: addr1, Nonce: 2
+	txHash3 := common.HexToHash("0xcccc") // Sender: addr2, Nonce: 1
+
+	// Initially index is empty
+	if hash := ReadTxSenderNonceEntry(db, addr1, 1); hash != nil {
+		t.Fatalf("index should be empty, got %x", hash)
+	}
+
+	WriteTxSenderNonceEntry(db, addr1, 1, txHash1)
+	WriteTxSenderNonceEntry(db, addr1, 2, txHash2)
+	WriteTxSenderNonceEntry(db, addr2, 1, txHash3)
+
+	// Verify indices
+	tests := []struct {
+		name   string
+		sender common.Address
+		nonce  uint64
+		expect *common.Hash
+	}{
+		{"addr1-nonce1", addr1, 1, &txHash1},
+		{"addr1-nonce2", addr1, 2, &txHash2},
+		{"addr2-nonce1", addr2, 1, &txHash3},
+		{"addr2-nonce2 (missing)", addr2, 2, nil},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ReadTxSenderNonceEntry(db, tc.sender, tc.nonce)
+			if tc.expect == nil {
+				if got != nil {
+					t.Errorf("expected nil, got %x", got)
+				}
+			} else {
+				if got == nil {
+					t.Errorf("expected %x, got nil", *tc.expect)
+				} else if *got != *tc.expect {
+					t.Errorf("expected %x, got %x", *tc.expect, *got)
+				}
+			}
+		})
+	}
+
+	// Verify Overwrite
+	newHash := common.HexToHash("0xdddd")
+	WriteTxSenderNonceEntry(db, addr1, 1, newHash)
+
+	if got := ReadTxSenderNonceEntry(db, addr1, 1); *got != newHash {
+		t.Fatalf("failed to overwrite index: expected %x, got %x", newHash, got)
+	}
+}
diff --git a/internal/ethapi/api_test.go b/internal/ethapi/api_test.go
index 6d55e2c44b..61ec8e3c91 100644
--- a/internal/ethapi/api_test.go
+++ b/internal/ethapi/api_test.go
@@ -4073,3 +4073,40 @@ func TestSendRawTransactionSync_Timeout(t *testing.T) {
 		t.Fatalf("expected ErrorData=%s, got %v", want, got)
 	}
 }
+
+func TestGetTransactionBySenderAndNonce(t *testing.T) {
+	t.Parallel()
+
+	key, _ := crypto.HexToECDSA("b71c73a37e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	addr := crypto.PubkeyToAddress(key.PublicKey)
+	nonce := uint64(0)
+	tx := types.NewTransaction(nonce, common.Address{0xaa}, big.NewInt(1000), 21000, big.NewInt(1000000000), nil)
+	signedTx, _ := types.SignTx(tx, types.HomesteadSigner{}, key)
+
+	genesis := &core.Genesis{
+		Config: params.TestChainConfig,
+		Alloc: core.GenesisAlloc{
+			addr: {Balance: big.NewInt(1000000000000000000)},
+		},
+	}
+
+	backend := newTestBackend(t, 1, genesis, ethash.NewFaker(), func(i int, b *core.BlockGen) {
+		if i == 0 {
+			b.AddTx(signedTx)
+		}
+	})
+
+	api := NewTransactionAPI(backend, new(AddrLocker))
+	ctx := context.Background()
+
+	result, err := api.GetTransactionBySenderAndNonce(ctx, addr, nonce)
+	if err != nil {
+		t.Fatalf("GetTransactionBySenderAndNonce failed: %v", err)
+	}
+	if result == nil {
+		t.Fatalf("Expected transaction, got nil")
+	}
+	if *result != signedTx.Hash() {
+		t.Errorf("Hash mismatch: have %x, want %x", *result, signedTx.Hash())
+	}
+}
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 754a771ab3..76d9080a7b 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -66,7 +66,6 @@ type Backend interface {
 	BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
 	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
 	BlockByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*types.Block, error)
-	GetTransactionBySenderAndNonce(ctx context.Context, sender common.Address, nonce uint64) (*common.Hash, error)
 	StateAndHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*state.StateDB, *types.Header, error)
 	StateAndHeaderByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*state.StateDB, *types.Header, error)
 	Pending() (*types.Block, types.Receipts, *state.StateDB)
@@ -87,6 +86,7 @@ type Backend interface {
 	TxPoolContent() (map[common.Address][]*types.Transaction, map[common.Address][]*types.Transaction)
 	TxPoolContentFrom(addr common.Address) ([]*types.Transaction, []*types.Transaction)
 	SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription
+	GetTransactionBySenderAndNonce(ctx context.Context, sender common.Address, nonce uint64) (*common.Hash, error)
 
 	ChainConfig() *params.ChainConfig
 	Engine() consensus.Engine
diff --git a/internal/ethapi/transaction_args_test.go b/internal/ethapi/transaction_args_test.go
index 30791f32b5..6182f866b9 100644
--- a/internal/ethapi/transaction_args_test.go
+++ b/internal/ethapi/transaction_args_test.go
@@ -389,6 +389,11 @@ func (b *backendMock) GetCanonicalTransaction(txHash common.Hash) (bool, *types.
 func (b *backendMock) TxIndexDone() bool                                        { return true }
 func (b *backendMock) GetPoolTransactions() (types.Transactions, error)         { return nil, nil }
 func (b *backendMock) GetPoolTransaction(txHash common.Hash) *types.Transaction { return nil }
+
+// GetTransactionHashBySenderAndNonce implements the Backend interface for testing.
+func (b *backendMock) GetTransactionBySenderAndNonce(ctx context.Context, sender common.Address, nonce uint64) (*common.Hash, error) {
+	return nil, nil
+}
 func (b *backendMock) GetPoolNonce(ctx context.Context, addr common.Address) (uint64, error) {
 	return 0, nil
 }