Our is a possessive determiner - not a verb- it can be used in past or present sentences. It is not past or present . They saw our dog on the road. They see our mother everyday.
The word "is" is present tense.
does is present tense, does is the third person singular form of do. You use does for he/she/it or singular noun subjects. He does his homework every night. She does...
A past participle ends in -ed or -en and it has two function; 1) adjective 2) part of a verb Past tense refers to a verb. (Please note that, past participles are not verbs.)