SELECT 
  combination 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 430 
  AND amount > 0 
  AND combination != ''

Query time 0.00047

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_options_inventory range pc pc 770 24 Using index condition; Using where

Result

combination
1194_22459
1194_22459_1195_22474
1194_22459_1195_22475
1194_22460
1194_22460_1195_22474
1194_22460_1195_22475
1194_22462
1194_22462_1195_22474
1194_22462_1195_22475
1194_22463
1194_22463_1195_22474
1194_22463_1195_22475
1194_22465
1194_22465_1195_22474
1194_22465_1195_22475
1194_22466
1194_22466_1195_22474
1194_22466_1195_22475
1194_22467
1194_22467_1195_22474
1194_22467_1195_22475
1194_22469
1194_22469_1195_22474
1194_22469_1195_22475
1194_22470
1194_22470_1195_22474
1194_22470_1195_22475
1194_22471
1194_22471_1195_22474
1194_22471_1195_22475
1194_22472
1194_22472_1195_22474
1194_22472_1195_22475
1194_22473