Melon seeds, like pumpkin seeds, can be toasted and eaten as a snack. Recipes don't warn about a need to reach high heat, so there's no reason to think they wouldn't be safe raw. And your melon is a variety of normal melon, not something exotic to be concerned about
I can find no evidence via internet search that the seeds of Piel de Sapo melons have any toxicity whatsoever.
Even if they did, eating a handful of seeds would be harmless. For example, while apple seeds are definitely toxic, you have to eat several dozen of them to feel any ill effects.