More granular vs less granular lead field in compound index

Working with Data
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#1

index:

{
  last_logged_in: -1, // in milliseconds
  age: 1,
  city: 1,
}

query:

user.aggregate([
  {
    $match: {
      age: { $gt: 18 },
      city: { $in: ["chicago", "paris"] }
    }
  },
  {
    $sort: {
      last_logged_in: -1
    }
  },
  {
    $limit: 10000
  }
])

The last_logged_in field is in milliseconds. So let’s further suppose that all documents hold unique values of this field.

Is this index useful at all in the $match stage to find the documents?

EDITED:

The better way to phrase this question is, would this index be more effective if the last_logged_in field is more granular or less granular? For example, milliseconds vs seconds vs hours vs days?

#2

Another thing to note is that the last_logged_in field is never used in the $match stage, but is always part of the $sort.