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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28b52535503da619c47f26028fc924434e51464e7af31ab45ac1b1b10554d7b0' 
  AND token = '+s7ECAbNqfhvKwtnRSqODAU6D76I3xNnE1MksxKlFI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

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