I recommend using Analysis Workspace for this.
First, add the unique visitors to the top of a freeform table.

Next, search for "Time spent on page - bucketed" in the filter.

If you mouse over the dimension in the list you will see a small caret symbol (>). Clicking on that allows you to see which buckets are available.

Since you are interested in buckets over 3 minutes, hold "ctrl" while selecting the buckets that are over 3 minutes.

Drag and drop this selection underneath the unique visitors metric in the freeform table.

Lastly, drag the page dimension you are interested in (e.g. page name, URL, etc.) into the table where it says "Drop a Dimension Here". The table will update with the number of unique visitors broken down by timed bucket and page.