SELECT id FROM kisten WHERE id NOT IN (SELECT id_kisten FROM artikel);

wobei kisten:
CREATE TABLE `kisten` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
PRIMARY KEY (`id`)
)

wobei artikel:
CREATE TABLE `artikel` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`id_kisten` int(10) DEFAULT NULL,
`name` varchar(50) NOT NULL,
PRIMARY KEY (`id`),
KEY `id_kisten` (`id_kisten`),
CONSTRAINT `artikel_ibfk_1` FOREIGN KEY (`id_kisten`) REFERENCES `artikel` (`id`) ON DELETE CASCADE
)

content:
select * from kisten;
+----+--------------+
| id | name |
+----+--------------+
| 1 | BIG CHEST |
| 2 | MIDDLE CHEST |
| 3 | LITTLE CHEST |
| 4 | MICRO CHEST |
+----+--------------+

select * from artikel;
+----+-----------+------+
| id | id_kisten | name |
+----+-----------+------+
| 1 | 1 | Pony |
+----+-----------+------+