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

Query time 0.00008

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_product_feature_variants.position, cscart_product_feature_variant_descriptions.variant",
      "temporary_table": {
        "table": {
          "table_name": "cscart_product_feature_variants",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "rows": 158,
          "filtered": 27.21518898,
          "attached_condition": "cscart_product_feature_variants.variant_id in (66,69,55,84,78,76,73,39,80,70,71,67,68,83,77,74,65,82,45,75,81,79,72,54,89,106,101,102,103,100,104,108,109,110,111,112,121,114,115,117,91,135,136)"
        },
        "table": {
          "table_name": "cscart_product_feature_variant_descriptions",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": [
            "smscrm_edev.cscart_product_feature_variants.variant_id",
            "const"
          ],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(cscart_product_feature_variant_descriptions.lang_code = 'ja')"
        }
      }
    }
  }
}