diff --git a/swh/icinga_plugins/deposit.py b/swh/icinga_plugins/deposit.py
--- a/swh/icinga_plugins/deposit.py
+++ b/swh/icinga_plugins/deposit.py
@@ -177,16 +177,13 @@
         metadata_objects = requests.get(
             f"{self.api_url}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
             f"?authority=deposit_client%20{self._provider_url}"
+            f"&after={start_datetime.isoformat()}"
         ).json()
         expected_origin = f"{self._provider_url}/{self._slug}"
 
-        # Filter out objects that were clearly not created by this deposit (ie. created
-        # before the deposit started, or that are from unrelated origins)
+        # Filter out objects that were clearly not created by this deposit
         relevant_metadata_objects = [
-            d
-            for d in metadata_objects
-            if d.get("origin") == expected_origin
-            and datetime.datetime.fromisoformat(d["discovery_date"]) >= start_datetime
+            d for d in metadata_objects if d.get("origin") == expected_origin
         ]
         if not relevant_metadata_objects:
             self.print_result(
diff --git a/swh/icinga_plugins/tests/conftest.py b/swh/icinga_plugins/tests/conftest.py
--- a/swh/icinga_plugins/tests/conftest.py
+++ b/swh/icinga_plugins/tests/conftest.py
@@ -1,16 +1,14 @@
-# Copyright (C) 2019  The Software Heritage developers
+# Copyright (C) 2019-2022  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-import time
-
 import pytest
 
 
 @pytest.fixture
 def mocked_time(mocker):
-    start_time = time.time()
+    start_time = 1646413359.0  # 2022-03-04-17:02:39Z
 
     time_offset = 0
 
diff --git a/swh/icinga_plugins/tests/test_deposit.py b/swh/icinga_plugins/tests/test_deposit.py
--- a/swh/icinga_plugins/tests/test_deposit.py
+++ b/swh/icinga_plugins/tests/test_deposit.py
@@ -213,7 +213,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         [
             {
                 "swhid": swhid,
@@ -295,7 +296,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         [
             {
                 "swhid": swhid,
@@ -375,7 +377,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         [
             {
                 "swhid": swhid,
@@ -450,7 +453,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         [
             {
                 "swhid": swhid,
@@ -516,7 +520,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         [
             {
                 "swhid": swhid,
@@ -633,18 +638,12 @@
             "discovery_date": "2999-03-03T10:48:47+00:00",
             "metadata_url": f"{BASE_WEB_URL}/the-metadata-url",
         },
-        {
-            # Filtered out, because too old
-            "swhid": swhid,
-            "origin": origin,
-            "discovery_date": "2022-03-03T09:48:47+00:00",
-            "metadata_url": f"{BASE_WEB_URL}/the-metadata-url",
-        },
     ]
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         metadata_list,
     )
 
@@ -706,7 +705,8 @@
     scenario.add_step(
         "get",
         f"{BASE_WEB_URL}/api/1/raw-extrinsic-metadata/swhid/{swhid}/"
-        f"?authority=deposit_client%20http://icinga-checker.example.org",
+        f"?authority=deposit_client%20http://icinga-checker.example.org"
+        f"&after=2022-03-04T17:02:39+00:00",
         metadata_list,
     )
     scenario.add_step(