SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc16129f597e3d53b3a6caf070143442eeda284ad4deec43cc152f9f0afae436' 
  AND token = 'QRUxq49Vpyfhqit2lvvSPHzb8QznfEVZztKRSFjSwpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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