static function retriveTokensByScope($scope, $domain = null) {
        $kind_schema = self::getGoogleAccessTokenKind();
        $str_query = "SELECT * FROM $kind_schema WHERE scopes='$scope'";
        if (!is_null($domain)) {
            $str_query = $str_query . " AND domain='$domain'";
        }
        return self::fetchAll($kind_schema, $str_query);
    }