Easiest way to get a single stat value from a REST API?

I am looking at Grafana to replace an internal developed dashboard. I have been able to convert most of my existing dashboards, but I’m having trouble with a set of single stat values and I’m not really sure what the best solution is.

My current dashboard has a page with 3 related values which are retrieved from a REST API. The data is aggregated from multiple sources and exposed as a single object. The existing response is as follows:

{
  "todo": 1,
  "processed": 10,
  "total": 11
}

Since I control the rest API that returns this I can change the output, however, the Simple JSON Datasource seems to be tailored more towards time based data.

What would be the easiest way to get the values on a dashboard?