FWIW, There are two main lounges in PRG.

The CSA lounge is open to SkyTeam and OneWorld elites, whereas the LH lounge is for Star.

The CSA lounge is actually not too shabby with high backed chairs and a nice view over the tarmac. Food selection is not too bad and certainly a lot better than at some European airports.

As some other posters have mentioned, as you are flying a SkyTeam airline, you will of course require SkyTeam Elite Plus to be able to gain entry. OW members can only access the lounge if departing on a OW member airline.