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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b16b4756bc03465683af01a3a68e507632c2c7a5ecfc47213b7528eb40a8bba' 
  AND token = 'GfzSkQvlFkC35gGE7VMwSQjx+L9cc3mS3gGxXRseIa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

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