How can I force wait for mongoose promise call to finish?

Question

I have the following code:

let id=null;
tokenModel.findOne({ tokens: { "$in" : [token]} }).then((_token)=> 
{
    if (_token)
        id = _token._id
    else
        id = 0

}).catch((err) => {
    console.log("tokenModel Error ", err)
})

const data = new userModel({
  token: id
  });


data.save().then(() => 
{
    res.json({"id": id})
}
   

I want to wait for tokenModel.findOne() to finish before proceeding with the rest of the code. As for now, userData.save() writes id=null instead of =0 or = _token._id (because promise have not ended yet). I could move everything inside .then() of findOne function but that would decrease readability and I really want to avoid that.

I have tried making the whole function as async, and then adding await:

await tokenModel.findOne({ tokens: { "$in" : [token]} }).then((_token)=> 
{
    if (_token)
        id = _token._id
    else
        id = 0

}).catch((err) => {
    console.log("tokenModel Error ", err)
})

but to no avail.