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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ae7d9ee75583a6cbb829181fe2b0793ed2004f40dd058e4050d88d3f57b253a' 
  AND token = '4mxYDBqf9ZykjPtK2eDZhgSRmkxe1TZIHL/K8vxbS0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

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