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 (
    68132, 68131, 68130, 68129, 68128, 68127, 
    68406, 68405, 70370, 70371, 70369, 
    72395, 72396, 72401, 72402, 74054, 
    74053, 74613, 74612, 74611, 74614, 
    76559, 76558, 77260, 77262, 77261, 
    78032, 78033, 78343, 78344, 78342, 
    79950, 79948, 79949, 79951, 80869, 
    80870, 80871, 80891, 80890, 80892, 
    80893, 80907, 80911, 80912, 80913, 
    80914, 80908, 80909, 80910, 81813, 
    81814, 82258, 82259
  )

Query time 0.00196

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": 54,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68132,68131,68130,68129,68128,68127,68406,68405,70370,70371,70369,72395,72396,72401,72402,74054,74053,74613,74612,74611,74614,76559,76558,77260,77262,77261,78032,78033,78343,78344,78342,79950,79948,79949,79951,80869,80870,80871,80891,80890,80892,80893,80907,80911,80912,80913,80914,80908,80909,80910,81813,81814,82258,82259)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}