Oh it does exist. It may be updated but it exists.
In 1948 The Finno- Soviet Treaty was signed
The text is here
Considering Finland’s desire to remain outside the conflicting interests of the Great Powers; and Expressing their firm endeavour to collaborate towards the maintenance of international peace and security in accordance with the aims and principles of the United Nations Organization:
Have for this purpose agreed to conclude the present Treaty and have appointed as their Plenipotentiaries:
The President of the Republic of Finland: Mauno Pekkala, Prime Minister of the Republic of Finland;
The Presidium of the Supreme Soviet of the U.S.S.R.: Viacheslav Mihailovich Molotov, Vice-Chairman of the Council of Ministers of the U.S.S.R. and Minister for Foreign Affairs,
who, after exchange of their full powers, found in good and due form, have agreed on the following provisions:
Article 1
In the eventuality of Finland, or the Soviet Union through Finnish territory, becoming the object of an armed attack by Germany or any state allied with the latter, Finland will, true to its obligations as an independent state, fight to repel the attack. Finland will in such cases use all its available forces for defending its territorial integrity by land, sea, and air, and will do so within the frontiers of Finland in accordance with obligations defined in the present agreement and, if necessary, with the assistance of or jointly with, the Soviet Union.
Article 4
The High Contracting Parties confirm their pledge, given under Article 3 of the Peace Treaty signed in Paris on February 10, 1947, not to conclude any alliance or join any coalition directed against the other High Contracting Party.
The treaty was updated BUT Finland’s neutrality remains the same:
The new agreement — Russia’s first political treaty with a Western country — replaces the 1948 Treaty on Friendship, Cooperation and Mutual Assistance, which required Finland to help defend the Soviet Union against any attack through Finnish territory.
Finland and Russia have (long) now committed themselves not to use force against each other and to respect their 800-mile border. They also promise to respect the rights of each other’s citizens on their territories.
Finland, which shares a 1,300-kilometer border with Russia, has long maintained neutrality and sought to play the role of an intermediary between Moscow and the West.
The Foreign Ministry added that it believes Finland’s NATO membership will stand in violation of the 1947 Paris Peace Treaty and the 1992 Russian-Finnish bilateral relations treaty.
“Taking into account the current indifference of the collective West toward international law, this behavior is the new normal,” the statement concludes.
As mentioned Finland is directly related to the Arctic encirclement/confrontation of Russia