const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

fetch('https://blackbox.dasha.ai/api/v1/misc/concurrency', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "active": 123,
  "concurrency": 123
}