решил проблему немного переделав запрос
select hrs.tid from helpdesk_route_uids hru, helpdesk_route_steps hrs
where hrs.rid=hru.rid
and hrs.tid=ht.id
and hru.rid in (select rid from helpdesk_route_uids where uid = %user_id%)
group by hru.rid having count(hru.rid) = 1