SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f3683df1bfd5308b79a32af70971744f699f18c98b7544a1b43168b84ee97c3' 
  AND token = 'MNNxGfwYyy9WCnAEuCZWEcOk1R5wGPndzIw7qFVOc0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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