If some product key has 'acts_used': 0, that means that there no current activations on this key.
If it also has 'total_deacts': 0, that means that key have never been deactivated previously. Which also means that it was not previously activated.
It can be only curently activated and as it is now 'acts_used': 0 that means that it was never activated.
So keys which have 'acts_used': 0 and 'total_deacts': 0 are those who never were activated.
What do you think about this logic, do you agree?