def METHOD_NAME(client_key, client_secret):
    """
    Query the vistara API and get an access_token
    """
    if not client_key and not client_secret:
        log.error(
            "client_key and client_secret have not been specified "
            "and are required parameters."
        )
        return False
    method = "POST"
    url = "https://api.vistara.io/auth/oauth/token"
    headers = {
        "Content-Type": "application/x-www-form-urlencoded",
        "Accept": "application/json",
    }
    params = {
        "grant_type": "client_credentials",
        "client_id": client_key,
        "client_secret": client_secret,
    }
    resp = salt.utils.http.query(
        url=url, method=method, header_dict=headers, params=params, opts=__opts__
    )
    respbody = resp.get("body", None)
    if not respbody:
        return False
    access_token = salt.utils.json.loads(respbody)["access_token"]
    return access_token