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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3a31f7523ae5d5f04e8ac4fc9ad07baee2cac03fc07652fbb5f61941ac573a8' 
  AND token = 'DyeJl13BIkJWQrGZB+8ZXEnAZQga1zT6XHXaSb5pbMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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