public static function usesAllIndexes($sql): bool
    {
        $qh = self::getInstance()->sql_query('EXPLAIN ' . $sql);

        if (!$qh->rowCount()) {
            return false;
        }

        while ($q = $qh->fetch(PDO::FETCH_ASSOC)) {
            if (!$q['key']) {
                return false;
            }
        }

        return true;
    }