I believe the biggest obstacle such idea has is the volume which would be necessary to fulfill the time requirements you are talking about.

Even in large and popular casinos lotteries are set up as weekly events or daily events, so on order for your idea to actually work, you would need to secure enough users from the beginning, so people won't have to wait too much for a smart contract settlement.

You would also need to do such thing using a Blockchain which is fast and with low fees, because if someone likes the service they will try to buy tickets several times or many times in the day.