Fixed parsing of first in the event it was an Expression.

Author: mikebronner

src/CacheKey.php

@@ -80,7 +80,11 @@ protected function getColumnClauses(array $where) : string
         if ($where["type"] !== "Column") {
             return "";
         }
-
+        
+        if ($where["first"] instanceof Expression) {
+            $where["first"] = $this->expressionToString($where["first"]);
+        }
+        
         return "-{$where["boolean"]}_{$where["first"]}_{$where["operator"]}_{$where["second"]}";
     }