SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dfc31b455dab15af9156e17ee1999476fc4a86d1d65140aba5bcd5e6248830a' 
  AND token = 'pU/cwEZb8Qbc/KNvlqh7gqOVpe6juuFt3d99vzn/1/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}