Habs auch ohne toller Tips hinbekommen.
Für alle die's interessiert:
PHP-Code:
SELECT location.loc_id, location.txt_var FROM `locations` location
RIGHT JOIN ( SELECT loc_id,txt_var FROM `locations` WHERE txt_var =12345 ) AS loc ON location.loc_id = loc.loc_id
WHERE location.txt_var != loc.txt_var LIMIT 0 , 30