SELECT 
  v.variant_id, 
  v.product_id, 
  vd.variant, 
  vf.position, 
  vf.color 
FROM 
  cscart_product_features_values v 
  LEFT JOIN cscart_product_feature_variant_descriptions vd ON v.variant_id = vd.variant_id 
  AND vd.lang_code = 'en' 
  LEFT JOIN cscart_product_feature_variants vf ON v.variant_id = vf.variant_id 
WHERE 
  1 
  AND v.feature_id = 1330 
  AND v.product_id IN (
    '40232', '40301', '40300', '40299', 
    '40298', '40297', '40296', '40295', 
    '40294', '40293', '40292', '40291', 
    '40290', '40289', '40288', '40287', 
    '40286', '40285', '40284', '40283', 
    '40282', '40281', '40280', '40279'
  )

Query time 0.00134

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "23.00"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "v",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id",
            "feature_id"
          ],
          "key_length": "6",
          "rows_examined_per_scan": 25,
          "rows_produced_per_join": 25,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "3.00",
            "eval_cost": "2.50",
            "prefix_cost": "5.50",
            "data_read_per_join": "19K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id"
          ],
          "attached_condition": "((`cscartdb`.`v`.`feature_id` = 1330) and (`cscartdb`.`v`.`product_id` in ('40232','40301','40300','40299','40298','40297','40296','40295','40294','40293','40292','40291','40290','40289','40288','40287','40286','40285','40284','40283','40282','40281','40280','40279')))"
        }
      },
      {
        "table": {
          "table_name": "vd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "cscartdb.v.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 25,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "6.25",
            "eval_cost": "2.50",
            "prefix_cost": "14.25",
            "data_read_per_join": "75K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      },
      {
        "table": {
          "table_name": "vf",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "cscartdb.v.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 25,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "6.25",
            "eval_cost": "2.50",
            "prefix_cost": "23.00",
            "data_read_per_join": "28K"
          },
          "used_columns": [
            "variant_id",
            "color",
            "position"
          ]
        }
      }
    ]
  }
}

Result

variant_id product_id variant position color
5296 40232 6" 0 #000000
5297 40279 7" 1 #000000
5298 40280 8" 2 #000000
5296 40281 6" 0 #000000
5297 40282 7" 1 #000000
5298 40283 8" 2 #000000
5296 40284 6" 0 #000000
5297 40285 7" 1 #000000
5298 40286 8" 2 #000000
5296 40287 6" 0 #000000
5297 40288 7" 1 #000000
5298 40289 8" 2 #000000
5296 40290 6" 0 #000000
5297 40291 7" 1 #000000
5298 40292 8" 2 #000000
5296 40293 6" 0 #000000
5297 40294 7" 1 #000000
5298 40295 8" 2 #000000
5296 40296 6" 0 #000000
5297 40297 7" 1 #000000
5298 40298 8" 2 #000000
5296 40299 6" 0 #000000
5297 40300 7" 1 #000000
5298 40301 8" 2 #000000