Time tables? Forget them! Yeast have no concept of time. They do there thing according to the environment they live in. It's possible they slowed down (probable) but if they were at full speed, it may not be much. They make their own heat!
To be honest, I rarely ferment above above 62 anymore. (depends on the yeast and the style of beer) so it might be fine. Which yeast did you use
In the end the best thing is to let it ride, then take a hydrometer reading and see where the fermentation is at. It may have changed, meaning it might take a bit longer. On the bright side, that might actually be a BETTER temperature for that yeast! If the majority of the primary fermentation is over, then you can safely bring it up to 70 ish for a couple of days to clean up.