What species is this lizard?
By the picture and the official distribution it looks to be as you said a Lacerta viridis.

Some references and distribution here: 


https://www.iucnredlist.org/species/61530/12507156
https://commons.wikimedia.org/wiki/Lacerta_viridis
http://reptile-database.reptarium.cz/species?genus=Lacerta&amp;species=viridis


In Western Europe we have a brother specie Lacerta bilineata. 

Example in Geneva:



The distribution maps shows that Lacerta viridis is mainly present in Easter Europe (including Hungary) and Lacerta bilineata is present in the Western Europe.

Both species are similar and the male get the throat blue generally during the breeding season. 

This site have also a description of the specie.