Though you can use restore key, SEPM won't be able to process it.
To perform disaster recovery I would suggest to install the same version of SEPM to avoid any kind of database corruption.
I am assuming SEPM is not on the latest version, after successfully database restore, I would recommend to upgrade the SEPM to the latest version i.e SEP 12.1 RU6 & then push out new package.
By doing this SEPM & SEP clients both will be upgraded to the latest version.