SELECT 
  * 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variant_descriptions.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'es' 
WHERE 
  cscart_product_feature_variants.variant_id = 102

Query time 0.00071

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.00"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_feature_variants",
          "access_type": "const",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "url",
            "color",
            "position"
          ]
        }
      },
      {
        "table": {
          "table_name": "cscart_product_feature_variant_descriptions",
          "access_type": "const",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "const",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "3K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "description",
            "page_title",
            "meta_keywords",
            "meta_description",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

variant_id feature_id url color position variant description page_title meta_keywords meta_description lang_code
102 18 0 Garmin <p><b>Garmin Ltd.</b>, incorporated in Schaffhausen, Switzerland, is the parent company of a group of companies founded in 1989 by Gary Burrell and Min Kao (hence the name GarMin), that develops consumer, aviation, and marine technologies for the Global Positioning System. Its subsidiary <b>Garmin International, Inc.</b> serves as headquarters for the Garmin Limited companies and is located in Olathe, Kansas in the United States. The largest operating subsidiary and primary production facility of Garmin Limited is <b>Garmin (Asia) Corporation</b>, located in Xizhi District, Taiwan, a district of New Taipei City.<br></p> es