Maximum temperature for thawing meat
You wouldn't want to exceed 100F, especially if you don't have good temperature regulation.  Above this temperature (especially in fish) you'll start to see the texture begin to change.

But, if all you're trying to do is thaw the meat, it's more important to circulate the water than to have the water at a warm temperature.  Water with strong convection currents that's even just 10F higher than your target "thawed" temperature (e.g. 35F) will thaw way faster than putting it in a still pot of water at 100F.

And, as an added bonus, bacteria grows fastest at ~107F.  So the outside of your meat exposed is to temperature near 107F becomes unsafe in about 4h.  In contrast, you can safely leave it in water at 86F for 7h and at room temperature 68F water for 18 hours.

So, moral of the story: Put it in a pot in the sink with the water dripping into the pot (to create circulation), and it will thaw fast but you don't need to worry if you forget about it.