It's been a few years since I was in the same position (September 2013), but when I was last in Praslin, the airport staff offered to change flights to earlier in the day for €10 per ticket. This wasn't advertised, but we found out once we enquired, as we had arrived at the airport quite early from La Digue (definitely worth a visit too).

We ended up taking up the offer, as from memory there was no lounge for us to access there, but at SEZ there is the lounge operated by Air Seychelles. Nothing too special, but it provided refreshments, food, showers, air conditioning, and a view of the tarmac.