SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31e2660577186673d912b6210d881a6ee07f0300280974b839fa7f5c502b9c05' 
  AND token = 'zZdqV40f3/GiwAY5FdN7KiusioPj8Bcmq4qrawbnLRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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