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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c15af40f808f6b5115f414690427ddd31e065b6e7e5444857e8547f5ada1d0a' 
  AND token = 'fx7HO8cAiw3exwPtpJIOB77tvhWienJmN4mQbuD4czI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE								Impossible WHERE noticed after reading const tables