You can book flights on cubajet.com or aerogaviota.com from Havana to Cayo Las Brujas (Around 225$ US return) Cayo Las Brujas is about a 5 or 10 minute taxi ride to the Royalton. They are only around 50 seat aircraft so book well in advance.

I would doubt very much if you could do 410 km in 4.5 hours, more likely 6+ hours.