diff --git a/framework/i18n/DbMessageSource.php b/framework/i18n/DbMessageSource.php
index eccc7fbd159..68f183f0444 100644
--- a/framework/i18n/DbMessageSource.php
+++ b/framework/i18n/DbMessageSource.php
@@ -39,12 +39,6 @@
  */
 class DbMessageSource extends MessageSource
 {
-    /**
-     * Prefix which would be used when generating cache key.
-     * @deprecated This constant has never been used and will be removed in 2.1.0.
-     */
-    const CACHE_KEY_PREFIX = 'DbMessageSource';
-
     /**
      * @var Connection|array|string the DB connection object or the application component ID of the DB connection.
      *