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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68876117b6c2936cffc6cb89def68255c5181295b46d5a0d04db66e52545ca22' 
  AND token = 'u6YzBkXTocHv7sG9edDqRpW6hdpI3vwRdNmOOdFWb3E=' 
  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