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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a6be36b3b1275ac03aa77c3f2121ad50f9e90e1554c5b0854c9b7ee2b4d90f6' 
  AND token = 'SNtLPrvyclH4fbtVqSZq/B3WX+OdVdVbLr6TDP29F9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

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