long integer - exclude many users in mysql -

thank in advance help. have make exclusion of users, problem takes long (about 5 hours or more) in database have 800,000 users of exclude around 580000 users (i 220000 users not repeated).

1. to make first method:

select iduser userstotal iduser not in( select iduser users220000)

(this simplified example of that's idea) takes 5 hours or more perform query.

i thinking of php script add in array of users , go excluding repeated.

that advise me optimize sql query or optimum method this.

• for reference use myisam

i rewrite query as

select   ut.iduser     userstotal ut    not exists (            select  u2.iduser                users220000 u2               u2.iduser = ut.iduser          ) 

and make sure iduser of userstotal table indexed.

i doubt index on users220000 make difference wouldn't hurt either.

edit

thanks ronnis spotting missing clause.