SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c665f68515cc44328a0766944d41723b579a2c1248c16765680b44a0058413cb' 
  AND token = 'm4TYFc+g2JrbykBWXEQqWPHSMtwexnsk0VFzyc91hps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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