Попробуйте:
select id, login, proxy FROM acc WHERE STATUS='{-Variable.status_bd-}' ORDER BY use_time LIMIT 1;
или так:
select id, login, proxy FROM acc WHERE STATUS=`{-Variable.status_bd-}` ORDER BY use_time LIMIT 1;
или так:
select id, login, proxy FROM acc WHERE STATUS={-Variable.status_bd-}...