diff --git a/ydb/core/kqp/common/kqp_tx.cpp b/ydb/core/kqp/common/kqp_tx.cpp
index 50ac4a55fcac..730798b321f7 100644
--- a/ydb/core/kqp/common/kqp_tx.cpp
+++ b/ydb/core/kqp/common/kqp_tx.cpp
@@ -157,7 +157,8 @@ bool NeedSnapshot(const TKqpTransactionContext& txCtx, const NYql::TKikimrConfig
 {
     Y_UNUSED(config);
 
-    if (*txCtx.EffectiveIsolationLevel != NKikimrKqp::ISOLATION_LEVEL_SERIALIZABLE)
+    if (*txCtx.EffectiveIsolationLevel != NKikimrKqp::ISOLATION_LEVEL_SERIALIZABLE &&
+        *txCtx.EffectiveIsolationLevel != NKikimrKqp::ISOLATION_LEVEL_SNAPSHOT_RO)
         return false;
 
     if (txCtx.GetSnapshot().IsValid())
diff --git a/ydb/core/kqp/common/kqp_tx.h b/ydb/core/kqp/common/kqp_tx.h
index ae355f3dc36d..85458667575f 100644
--- a/ydb/core/kqp/common/kqp_tx.h
+++ b/ydb/core/kqp/common/kqp_tx.h
@@ -256,8 +256,7 @@ class TKqpTransactionContext : public NYql::TKikimrTransactionContextBase  {
                 break;
 
             case Ydb::Table::TransactionSettings::kSnapshotReadOnly:
-                // TODO: (KIKIMR-3374) Use separate isolation mode to avoid optimistic locks.
-                EffectiveIsolationLevel = NKikimrKqp::ISOLATION_LEVEL_SERIALIZABLE;
+                EffectiveIsolationLevel = NKikimrKqp::ISOLATION_LEVEL_SNAPSHOT_RO;
                 Readonly = true;
                 break;
 
diff --git a/ydb/core/kqp/executer_actor/kqp_planner.cpp b/ydb/core/kqp/executer_actor/kqp_planner.cpp
index 1ec9dc84415f..929a3f01863a 100644
--- a/ydb/core/kqp/executer_actor/kqp_planner.cpp
+++ b/ydb/core/kqp/executer_actor/kqp_planner.cpp
@@ -187,8 +187,8 @@ std::unique_ptr<TEvKqpNode::TEvStartKqpTasksRequest> TKqpPlanner::SerializeReque
     request.SetTxId(TxId);
     if (LockTxId) {
         request.SetLockTxId(*LockTxId);
+        request.SetLockNodeId(LockNodeId);
     }
-    request.SetLockNodeId(LockNodeId);
     ActorIdToProto(ExecuterId, request.MutableExecuterActorId());
 
     if (Deadline) {
diff --git a/ydb/core/protos/kqp.proto b/ydb/core/protos/kqp.proto
index 45f35e5404dd..bc1280648e3e 100644
--- a/ydb/core/protos/kqp.proto
+++ b/ydb/core/protos/kqp.proto
@@ -64,6 +64,7 @@ enum EIsolationLevel {
     ISOLATION_LEVEL_READ_COMMITTED = 2;
     ISOLATION_LEVEL_READ_UNCOMMITTED = 3;
     ISOLATION_LEVEL_READ_STALE = 4;
+    ISOLATION_LEVEL_SNAPSHOT_RO = 5;
 };
 
 enum EQueryReplyFlags {