SELECT 
  cscart_product_feature_variants.variant_id, 
  cscart_product_feature_variants.position, 
  cscart_product_feature_variants.color, 
  cscart_product_feature_variant_descriptions.variant 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variants.variant_id = cscart_product_feature_variant_descriptions.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'fr' 
WHERE 
  cscart_product_feature_variants.variant_id IN (
    39, 65, 45, 66, 67, 68, 69, 70, 71, 72, 73, 
    54, 74, 75, 76, 77, 78, 79, 80, 81, 82, 
    55, 83, 84, 100, 101, 102, 103, 104, 89, 
    106, 91, 108, 109, 110, 111, 114, 121, 
    112, 115, 117, 135, 136
  ) 
ORDER BY 
  cscart_product_feature_variants.position ASC, 
  cscart_product_feature_variant_descriptions.variant ASC

Query time 0.00071

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "154.81"
    },
    "ordering_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_product_feature_variants",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "variant_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 43,
            "rows_produced_per_join": 43,
            "filtered": "100.00",
            "index_condition": "(`danishecarter_31jan`.`cscart_product_feature_variants`.`variant_id` in (39,65,45,66,67,68,69,70,71,72,73,54,74,75,76,77,78,79,80,81,82,55,83,84,100,101,102,103,104,89,106,91,108,109,110,111,114,121,112,115,117,135,136))",
            "cost_info": {
              "read_cost": "94.61",
              "eval_cost": "8.60",
              "prefix_cost": "103.21",
              "data_read_per_join": "113K"
            },
            "used_columns": [
              "variant_id",
              "color",
              "position"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_product_feature_variant_descriptions",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "variant_id",
              "lang_code"
            ],
            "key_length": "9",
            "ref": [
              "danishecarter_31jan.cscart_product_feature_variants.variant_id",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 43,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "43.00",
              "eval_cost": "8.60",
              "prefix_cost": "154.81",
              "data_read_per_join": "130K"
            },
            "used_columns": [
              "variant_id",
              "variant",
              "lang_code"
            ]
          }
        }
      ]
    }
  }
}