SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    68479, 83944, 83945, 85457, 85458, 86486, 
    86485, 86484, 86493, 86492, 86928, 
    86929, 86970, 86971, 86972, 86973, 
    86974, 86975, 86976, 86977, 86978, 
    86979, 86980, 86981, 86982, 86983, 
    86984, 86985, 86986, 86987, 86988, 
    86989, 86990, 86991, 86992, 86993, 
    86994, 86995, 86996, 86997, 87173, 
    87174, 87172, 87170, 87261, 87260, 
    87259, 87258, 87171, 87221, 87222, 
    87223, 87331, 87330, 87332, 87334, 
    87333
  )

Query time 0.00216

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 57,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68479,83944,83945,85457,85458,86486,86485,86484,86493,86492,86928,86929,86970,86971,86972,86973,86974,86975,86976,86977,86978,86979,86980,86981,86982,86983,86984,86985,86986,86987,86988,86989,86990,86991,86992,86993,86994,86995,86996,86997,87173,87174,87172,87170,87261,87260,87259,87258,87171,87221,87222,87223,87331,87330,87332,87334,87333)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}