Issue #3268849 by jsacksick: Add indexes to the log template & category ID fields.

modules/log/src/LogStorageSchema.php

@@ -21,6 +21,8 @@ class LogStorageSchema extends SqlContentEntityStorageSchema {
         'source_entity_type',
       ],
       'created' => ['created'],
+      'category_id' => ['category_id'],
+      'template_id' => ['template_id'],
     ];
     return $schema;
   }