Get private keys for the liteproxy server

Example response

{
  "keys": [
    {
      "rps": 10,
      "private_key": "da6b1b6663a0e4d18cc8574ccd9db5296e367dd9324706f3bbd9eb1cd2caf0bf",
      "date_create": 1690889913000
    }
  ]
}