It comes down to the luck of the draw I suppose. Riot will sometimes check your account at random when you or someone else submits a ticket in regards to the account in question. This is like mentioned above, completely random and doesn't really serve any purpose other than being unorthodox checkups.
Rarely will riot ever search for elo boosting because the majority of the procedures are done through VPN's and can therefore not be linked to any accounts in particular. Riot may have the right to ban your account for any reason at any given time, but just because they do, it doesn't mean they will. They still follow protocol.
Aside from this, elo boosting account should otherwise be completely risk free, other than a very small percentage of punishment. I'd say the odds to being punished are 99,9 to 0,01.
Please remember that you can really only be safe if you do this with the use of a VPN.