SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6998bd4152864b6777677c3966c73981f0374967e576f865493b8ba9abaa7d6f' 
  AND token = 'iua4Wln43tqcoQArIibzgwiOJp728s5bRVpE6OYHsLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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