By quick-prepare ravioli, you mean without sauce, right?
It's fine to (and you should) cover the pot to bring the water to a boil. Incidentally, it's best to start with cold water from the tap, hot tap water will likely be more contaminated, possibly with lead. Once the water is boiling, add the salt, then the pasta. Adding the pasta will bring down the temperature of the water, so you can briefly put the lid back on to more quickly bring the water back up to the boil.
Once the water is boiling again, it's recommended that you keep it uncovered because pasta water is very prone to foaming up and boiling over. It's a royal pain when that happens, so think before covering pasta while it is boiling. If your pot is big enough and you watch carefully, you can save some energy by cooking with the lid on, just be careful because boil-overs happen quickly. Obviously, it's good to have a stockpot with a glass lid for that.
EDIT: Now that I've covered the conventional wisdom, I'd also encourage you to read this: A to Pasta: is simmering equivalent to roiling boil?, especially the Serious Eats link. I admit, I haven't done it (set in my ways, I suppose), but considering your set-up, you might find the method works better for you.