diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index c8e03e0e48..7d456f91f5 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,8 @@ Added
   #5778 #5789 #5817 #5795 #5830 #5833 #5834 #5841 #5840 #5838 #5842 #5837 #5849 #5850
   Contributed by @cognifloyd
 
+* Added a joint index to solve the problem of slow mongo queries for scheduled executions. #5805
+
 
 3.8.0 - November 18, 2022
 -------------------------
diff --git a/st2common/st2common/models/db/execution_queue.py b/st2common/st2common/models/db/execution_queue.py
index 8db0993363..a45267a4d7 100644
--- a/st2common/st2common/models/db/execution_queue.py
+++ b/st2common/st2common/models/db/execution_queue.py
@@ -77,6 +77,11 @@ class ActionExecutionSchedulingQueueItemDB(
             {"fields": ["liveaction_id"], "name": "lv_ac_id"},
             {"fields": ["original_start_timestamp"], "name": "orig_s_ts"},
             {"fields": ["scheduled_start_timestamp"], "name": "schd_s_ts"},
+            # Adding a union index speeds up the query action_execution_scheduling_queue_item_d_b
+            {
+                "fields": ["scheduled_start_timestamp", "original_start_timestamp"],
+                "name": "schd_orig_s_ts",
+            },
         ]
     }