The man, identified only as Vitali S. in line with Polish privacy rules, was found to have filmed a customs warehouse in the town of Chełm, which prosecutors said was to be set on fire.
Investigators said he sent the footage and information about the site to the person who had commissioned the task, and was paid about PLN 1,400 (roughly EUR 320) in cryptocurrency.
Poland's Internal Security Agency (ABW) said he was recruited and given instructions via the Telegram messaging app.
The Lublin District Court also banned him from holding public rights for nine years and fined him PLN 1,500 (EUR 343).
He was additionally charged with drug possession.
The trial, held on Monday, was closed to the public on grounds of state interest.
The man was arrested in August last year.
Jacek Dobrzyński, spokesman for Poland's minister coordinating the special services, said on X that ABW officers had detected and thwarted the plot before it could be carried out.
The verdict is not final and can be appealed.
(ał)
Source: PAP