SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2710e495b6f2c39056aaddf5770520981447865c5bfec616a1f902e94f7f19d5' 
  AND token = 'nS/PsQi1MopOUGad4eETKpgGwQRa5se45+xpyWRZQbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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