Hello Joszef,
Yes,
Curtis is right: your coin corresponds to Alföldi 26, 121. As a matter of fact, it is from the same pair of dies as the coin in
Oxford listed by Alföldi.
I don't have any other similar coin in my database, so I think yours is the second known exemplary.
The issue it belongs to is earlier than 280 AD (4th em. following my own classification). Congratulations,
S.
Estiot