I have fallen in love with this adventure card game and would like to check the art of each cards in more detail, especially the art of spell cards since they are more than static image. Does such database exist for each Adventure Paths or Class Decks, or is my only option to search and admire them individually?
No database of the sort exists, to the best of my knowledge. You can find scans of basically every card online if you look hard enough, but it certainly would not be higher resolution than the art for your printed card.
Some of the art pieces come from various products in the RPG line and can be found in higher detail there. You may find higher resolution versions of some art pieces on sites like deviantart if the artist shared it there after being commissioned by paizo to create it. But all of that is very hit-or-miss and you would need to do lots of digging to find even one piece of art because there is very little info to go on to start your search.