def parse_sas_token(sas_token):
    """Parse a SAS token into its components.

    :param sas_token: The SAS token.
    :type sas_token: str
    :rtype: dict[str, str]
    """
    sas_data = {}
    token = sas_token.partition(' ')[2]
    fields = token.split('&')
    for field in fields:
        key, value = field.split('=', 1)
        sas_data[key.lower()] = value
    return sas_data