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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ec66f0c0c59e515444d639b541757da6cb3f9a18e625bc0a548860bfa087f2f' 
  AND token = 'uK6OUFbxm7gWIDf1fF8jYz1ArODsRJQ2X7HzqIxuM5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

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