Any person who has exhausted all administrative remedies provided by law and who is aggrieved by a final decision in a contested case, whether such decision is affirmative or negative in form, shall be entitled to judicial review thereof, as provided in sections 536.100 to 536.140, unless some other provision for judicial review is provided by statute; provided, however, that nothing in this chapter contained shall prevent any person from attacking any void order of an agency at any time or in any manner that would be proper in the absence of this section. If the agency or any board, other than the administrative hearing commission, established to provide independent review of the decisions of a department or division that is authorized to promulgate rules and regulations under this chapter fails to issue a final decision in a contested case within the earlier of:
(1) Sixty days after the conclusion of a hearing on the contested case; or
(2) One hundred eighty days after the receipt by the agency of a written request for the issuance of a final decision,