SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  fv.position, 
  fvd.variant 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_feature_variants AS fv ON pfv.feature_id = fv.feature_id 
  AND pfv.variant_id = fv.variant_id 
  INNER JOIN cscart_product_feature_variant_descriptions AS fvd ON pfv.variant_id = fvd.variant_id 
  AND fvd.lang_code = 'ru' 
WHERE 
  pfv.feature_id IN (193, 3) 
  AND pfv.product_id IN (
    137, 88, 126, 31, 51358, 115, 80, 37, 11, 
    140, 41, 30, 90, 38, 124, 81, 56, 82, 116, 
    117, 125, 106, 39, 40, 22710, 22711, 
    17, 57, 122, 58, 5
  ) 
  AND pfv.lang_code = 'ru'

Query time 0.00298

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "37.03"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id",
            "feature_id",
            "lang_code"
          ],
          "key_length": "12",
          "rows_examined_per_scan": 63,
          "rows_produced_per_join": 63,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "7.18",
            "eval_cost": "6.30",
            "prefix_cost": "13.48",
            "data_read_per_join": "48K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`test_uchur_k`.`pfv`.`feature_id` in (193,3)) and (`test_uchur_k`.`pfv`.`product_id` in (137,88,126,31,51358,115,80,37,11,140,41,30,90,38,124,81,56,82,116,117,125,106,39,40,22710,22711,17,57,122,58,5)) and (`test_uchur_k`.`pfv`.`lang_code` = 'ru'))"
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "feature_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "test_uchur_k.pfv.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 4,
          "filtered": "6.81",
          "cost_info": {
            "read_cost": "15.75",
            "eval_cost": "0.43",
            "prefix_cost": "35.53",
            "data_read_per_join": "6K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`test_uchur_k`.`fv`.`feature_id` = `test_uchur_k`.`pfv`.`feature_id`)"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "test_uchur_k.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 4,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "1.07",
            "eval_cost": "0.43",
            "prefix_cost": "37.03",
            "data_read_per_join": "13K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id position variant
3 5 6 0 OSFA
193 5 1373 0 OSFA
3 11 6 0 OSFA
193 11 1373 0 OSFA
3 17 6 0 OSFA
193 17 1373 0 OSFA
3 30 25 0 размер L
193 30 1357 0 S
3 31 24 0 размер 2XL
193 31 1357 0 S
3 37 22 0 размер S
193 37 1357 0 S
3 38 26 0 размер XL
193 38 1357 0 S
3 39 26 0 размер XL
193 39 1357 0 S
3 40 26 0 размер XL
193 40 1357 0 S
3 41 26 0 размер XL
193 41 1357 0 S
3 56 6 0 OSFA
193 56 1373 0 OSFA
3 57 6 0 OSFA
193 57 1373 0 OSFA
3 58 6 0 OSFA
193 58 1373 0 OSFA
3 80 30 0 р.41
193 80 1390 0 41
3 81 6 0 OSFA
193 81 1373 0 OSFA
3 82 6 0 OSFA
3 88 12 0 3XL
193 88 1358 0 M
3 90 19 0 40x30
193 90 1371 0 30x30
3 106 6 0 OSFA
193 106 1373 0 OSFA
3 115 39 0 56-60
193 115 1375 0 56-60
3 116 39 0 56-60
193 116 1375 0 56-60
3 117 39 0 56-60
193 117 1375 0 56-60
3 122 40 0 62
193 122 1385 0 60
3 124 10 0 M
193 124 1357 0 S
3 125 10 0 M
193 125 1357 0 S
3 126 6 0 OSFA
193 126 1373 0 OSFA
3 137 8 0 S
193 137 1357 0 S
3 140 7 0 XL
193 140 1357 0 S
3 22710 26 0 размер XL
193 22710 1358 0 M
3 22711 26 0 размер XL
193 22711 1359 0 L
3 51358 25 0 размер L
193 51358 1358 0 M