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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '22519985544e2359152dea1834addde1b7d866b747db5c7b8523fb5a243fd96c' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

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