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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2a74c6ed9f5b7d1a56f17db40536402d50433e8d78743a156ef9f2c655a795c' 
  AND token = 'r7CpxP7sd71qPnbPjJVLoekmruuCzccacv6ZnGB3tDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

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