MYSQL - Indsæt hvis tabellen er tom

INSERT INTO `account_types`(`type`, `group`)
SELECT * FROM
(SELECT '400' `type`, 'test' `group` UNION ALL
 SELECT '401' `type`, 'test2' `group` UNION ALL
 SELECT '402' `type`, 'test3' `group`) A
WHERE NOT EXISTS (SELECT NULL FROM account_types B WHERE A.type=B.type);

Demo