Help with json and datetime .-.

[Matqyou]

I wanted to create a datetime.datetime.now() + timedelta(minutes=30)
and put this inside a json file

2018-10-25 12:13:53.99943

but then when i pull it out from json its no longer an object but a string, please help me how do i make it useable again .-.

and when i have it i define it as endtime and every time a function gets triggered it checks how much till you reached endtime and if you have already reached it it would say Ready!