Yes, there is a shortcut for commenting out lines in Python 3.6 (Spyder).
For Single Line Comment, you can use Ctrl+1. It will look like this #This is a sample piece of code
For multi-line comments, you can use Ctrl+4. It will look like this
#=============
\#your piece of code
\#some more code
\#=============
Note : \ represents that the code is carried to another line.