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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6649543d91e5dac88a1cbf47b9c346868dde70aebef9decc4129a8618af70f1' 
  AND token = 'o/Fi3O2/RMOYPxmEoXmw48VKYR9LPe2NVg1beazeF7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

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