I think the answer may be yes but I need to be sure...

If I query my table, and I have a WHERE and 2 AND clauses; do they each reduce the data set that the next clause has to deal with such that the query becomes leaner as it is processed or; do they all get applied at the same time, at the end of the query?

say I query this

Code MySQL:
, state
, town
from addresses as AD
left outer join 
possible_countries as PC
on PC.country = AD.country
and PC.state = AD.state
where AD.country = 'France'
AND AD.state = 'Quebec'
and '[mathematical calc here]'

Will the WHERE & 1st AND reduce the data that the 2nd AND must manipulate?