SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71a4c15fa2b60ee6c57a4fecadbf2404b753e6e159d34441183fd5dab9584ba7' 
  AND token = '/9XF5XGALCgovKf9wH/6ktXp1UB53VJXHzqKz6Ef1ZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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