SELECT a.`client_bid_id`
FROM `client_bid` a
WHERE a.`client_bid_blocked` = 'n'
AND NOT EXISTS
(
SELECT 1
FROM `client_login` b
WHERE b.`client_id` = a.`client_id`
AND b.`client_login_type` = 'success'
AND b.`client_login_date` > NOW() - INTERVAL 1 HOUR
)

SELECT a.`client_bid_id`
FROM `client_bid` a
LEFT JOIN `client_login` b ON (b.`client_id` = a.`client_id` AND b.`client_login_type` = 'success' AND b.`client_login_date` > NOW() - INTERVAL 1 HOUR)
WHERE a.`client_bid_blocked` = 'n'
AND b.`client_id` IS NULL

"id"	"select_type"	"table"	"type"	"possible_keys"	"key"	"key_len"	"ref"	"rows"	"Extra"
"1"	"PRIMARY"	"a"	"ALL"	\N	\N	\N	\N	"12"	"Using where"
"2"	"DEPENDENT SUBQUERY"	"b"	"ALL"	\N	\N	\N	\N	"1"	"Using where"

"id"	"select_type"	"table"	"type"	"possible_keys"	"key"	"key_len"	"ref"	"rows"	"Extra"
"1"	"SIMPLE"	"a"	"ALL"	\N	\N	\N	\N	"12"	"Using where"
"1"	"SIMPLE"	"b"	"ALL"	\N	\N	\N	\N	"1"	"Using where; Not exists; Using join buffer (Block Nested Loop)"