I was able to get it working like this:
select
es.id,
es.escalation_id,
es.escalation_user_id,
max(es.`level`) as 'cur_level',
es.dt_added,
es.status_type_id
from
ABCD.t_escalation_status es
where
(escalation_id, `level`) in (
select escalation_id, max(`level`) from...