Fixed expression manager selection by token

Fixed export notices about array

include/limesurvey/classes/expressions/LimeExpressionManager.php

@@ -3419,7 +3419,7 @@
 		$sql = "SELECT sv.var,sv.val
 			FROM sample_var as sv, `case` as c
 			WHERE c.sample_id = sv.sample_id
-			AND c.token = {$_SESSION['token']}";
+			AND c.token = '{$_SESSION['token']}'";
 
 		$queXSrs = $connect->GetAssoc($sql);