SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36ebc638f74b904cfa0ad6b8d5861c3d50ceb02c9da0ec6167df25d8b39050f9' 
  AND token = 'mqf/LGMPafuk798mMjvGkGBO+tg6knS16bVwL5+qp0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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