SELECT 
  product_variant, 
  category_variants 
FROM 
  cscart_ec_vendor_filter_map

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.06"
    },
    "table": {
      "table_name": "cscart_ec_vendor_filter_map",
      "access_type": "ALL",
      "rows_examined_per_scan": 5,
      "rows_produced_per_join": 5,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "2.06",
        "eval_cost": "1.00",
        "prefix_cost": "3.06",
        "data_read_per_join": "80"
      },
      "used_columns": [
        "product_variant",
        "category_variants"
      ]
    }
  }
}

Result

product_variant category_variants
1 5,6,7,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,78,80
2 45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,82
3 29,30,32,33,64,72,74,75,76
4 31,34,35,36,37,38,39,40,41,42
9 54,81,83