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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '458915473b99d305e4c7f9a5d602cfa2adbb5b8adf40a0310f81f9d120a7dffe' 
  AND token = 'QGjOFHxletrvgCiQpbLWB9pV6FpMvip6R8yuufYfYms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

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