curl --request GET \
  --url https://api.example.com/api/users/by-external-id/{external_id}

{
  "id": "<string>",
  "externalId": "<string>",
  "createdAt": "2023-12-25",
  "updatedAt": "2023-12-25",
  "createdBy": "<string>",
  "space": "production",
  "token": "<string>"
}