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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4356c68b8dfd8bb1b8a41090abd66208907f29c4b220afe07f39caaeb5fcee95' 
  AND token = 'YP5Q2QXVmJHuIyOoyYU3ZDbyYnGwQZH0G3odj5hQarI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

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