set random_page_cost = 2;
set enable_bitmapscan = false;
--
update pg_index set indisready = false, indisvalid = false where indexrelid = (select oid from pg_class where relname = 's_pk_action_at');
-- update pg_index set indisready = true, indisvalid = true where indexrelid = (select oid from pg_class where relname = 's_pk_action_at');

explain (analyze, buffers)
SELECT s.pk FROM s
INNER JOIN m ON m.pk = s.m_fk
WHERE
  s.status IN ('A', 'PD', 'P')
  AND (action_at <= '2018-09-06')
  AND s.status IN ('A', 'P')
  AND m.status = 'A';
