Sorry for the confusion around the queries. Both queries are causing trouble. We've noticed that just EXPLAINING the very simple queries takes forever.
After more digging it looks like this table has an inordinate number of indices (10 ish). There a whole buch of conditional indicies for other columns that we're not checking. The particular column that is causing us trouble exists in both a regular (con_id) and a composite index (con_id, somthing_else).
We checked on locks and don't see any ungranted locks. Would waiting on the AccessShareLock not appear in pg_locks?
Thanks!
Nik