QUERY PLAN
GroupAggregate (cost=0.28..91.38 rows=1 width=154)
Group Key: c.id
-> Nested Loop Left Join (cost=0.28..91.36 rows=1 width=154)
Join Filter: (c.id = cm.contact_id)
-> Index Scan using tbl_contacts_pkey on tbl_contacts c (cost=0.28..8.30 rows=1 width=150)
Index Cond: (id = 3642)
-> Seq Scan on tbl_contact_mobiles cm (cost=0.00..83.05 rows=1 width=8)
Filter: ((mp_open_id IS NOT NULL) AND (contact_id = 3642))