Hello,

In both cases I get a warning.

I think, it is a auto-cast problem. Please use the data base table instead of this query. Check out the true result using

SELECT
    `last_login`,
    (`last_login` - (NOW() - INTERVAL 3 YEAR))
FROM `mlf2_userdata`
WHERE `user_lock` = 0
    AND `user_type` = 0
    AND `inactivity_notification` = FALSE
ORDER BY `last_login` ASC;

/Micha