SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e3a1218a9237298588781a87fea40569be9b80b1df248b704e3b4158979246f' 
  AND token = 'pTvgW7XluUaLFchFyUAPC7X4vWc7mUtXdoHYv92nihY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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