help optimizing query

Hi all,

The situation: there are users in one table, and their access statistics 
in the other. Now I want to find users whose last access time was more 
than one month ago. As I've only had to write quite simple queries 
involving no sub-selects so far, I'd like to ask your opinion if this 
one scales at all or not.

SELECT u.login,last_use_time
FROM users u
JOIN (SELECT user_id, MAX(stop_time) AS last_use_time
       FROM stats
       GROUP BY user_id) AS s ON (u.id=s.user_id)
WHERE status='3' AND next_plan_id IS NULL
   AND last_use_time < now() - interval '1 month'
ORDER BY last_use_time;

It seems to do the job, but how good is it in the long run? Any way I 
could tweak it?

Thanks.