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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3873b523c9a1eed505f55bcfef257919a85bce9d87bd76ce199dd4bd9b10b70e' 
  AND token = 'ZLbURFTks1/gDDXAx/cKX+mhjHYFdq0VbMq9SKQH/lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

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