Are the scratches white, or are they the same color as the rest of the finish? If they are white- nothing will melt them back, so anything you put over it will still show the white scratch. If they are the same color, then you may be able to finish over it. I've done it many times; procedure as follows: 1. Wash the surface with naptha to remove any old wax, oils, and polish. Liberally wet a clean rag with the naptha, scrub the surface, then wipe with a clean dry rag. Repeat until no more dirt appears on the dry rag. WARNING: This may remove some of the finish to bare wood, if the lacquer is soft. If it does, you will need to strip to bare wood and start over.
2. You need to wash the cleaned finish with a strong detergent, such as Dirtex mixed in hot water, to remove any residue left by the naptha wash. Use a clean rag, wring it out, wipe down all surfaces, follow with a clean rag wrung out in clean water, then dry. 3. If the lacquer is still intact after the naptha and detergent wash, lightly scuff the surfaces with red or gray fine scothbrite. This will create a scratch pattern for the new finish. 4. You will need to pick up a vinyl sealer made for wood finishes and spray it, uncut, over all surfaces. This will seal the old lacquer and keep the new finish from lifting. 5. I would not spray an automotive clear over any old finish, even if it sealed with the vinyl sealer. I would use either furniture lacquer or a post- or pre- catalyzed furniture clear. 3 and 4 Alternative: apply clear shellac over the old lacquer to seal it, scuff lightly, then apply varnish by spray or brush over the shellac. The varnish can be scuffed between coats, and the final coat can be cut and buffed after a couple of weeks of cure time. I often wet sand furniture finishes to 1500 or 2000, then block with the grain with 0000 steel wool; this gives a satin sheen to the finish.
If you want to use SPI clear, you will have to strip to bare wood. If you do strip to bare wood, you will need to wash the stripped wood with a strong detergent, such as Dirtex mixed in hot water, washed and dried, then follow with clean water, wash and dry. This is to remove any stripper residue and any oils or silicones that may have penetrated into the wood.
So-there is no quick easy way to do this, at least not any that will hold up over time and look good.