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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '735bf92a15aa9cf3b04806d4889cc9d82eedb24ea93f4a918f824ab61154154c' 
  AND token = 'SN7T5F7GKlVoiaugSYnc8flajC5n9mz8CfprvVZ6DWM=' 
  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