You could easily used these to see a snake 10-20 ft away safely. I would also suggest another trick to use. If you can, you pack a small mirror metal or glass compact. And you reflect light under the ledge at the spot you are trying to look at. You get better clarity with more light as well, but only if there is not enough light. The binoculars work really well at close range and quite well at medium to long range. Just not as much magnification at longer ranges like some of the big ones.
I use them for hunting and spotting look at the occasional lizard pumping at me.
I own those binoculars and I have been on several herpetology field trips in the "snake country" of the southeast U.S. The short answer is no. It's dark under rock ledges, and fallen logs - or at least dim, and binoculars of any kind are of very limited help. If you were to be still and just observe they might help you distinguish fallen leaves from adjacent reptiles say, but under those circumstances you would be better off with a small telescope.
I consider these binoculars to be high resolution and optically clear. They provide sharp focus on insects and vegetation as well as inanimate objects from as close as 2 1/2 feet (approximate) to many yards away. The answer to your question depends upon your knowledge of snake species, your ability to ascertain distinguishing characteristics, whether the snakes are on the line of sight, and a host of other variables. Are they good binoculars? Yes. Those with whom I have shared them have remarked "these are amazing; I've never seen binoculars like this".