how i can make a not exists expression with a subquery

[catthecreator]

Hi!

Please tell me how I can create the following expression

select *
from `users`
where `channel_id` = 81
  and (not exists (select *
                     from `user_variables`
                     where `users`.`id` = `user_variables`.`user_id`
                       and `id` in ('489')
                       and `value` = 123
          ))

For one field, I can use the construction
!relation.column

But I need not_exists by subquery

Thanks for your attention :)