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 = 'en' 
WHERE 
  cscart_product_feature_variants.variant_id = 86

Query time 0.00029

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": {
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            "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",
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          "key": "PRIMARY",
          "used_key_parts": [
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          ],
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          ],
          "rows_examined_per_scan": 1,
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          "used_columns": [
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            "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
86 18 0 Adidas <p></p><p><b>Adidas AG</b>&nbsp; is a German multinational corporation that designs and manufactures sports clothing and accessories based in Herzogenaurah, Bavaria, Germany. It is the holding company for the Adidas Group, which consists of the Reebok sportswear company, TaylorMade-Adidas golf company (including Asworth), and Rockport. Besides sports footwear, Adidas also produces other products such as bags, shirts, watches, eyewear, and other sports- and clothing-related goods. Adidas is the largest sportwear manufacturer in Germany and Europe and the second biggest sportswear manufacturer in the world.</p><br><p></p> en