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 = 'vi' 
WHERE 
  pfv.variant_id IN (
    75757, 75754, 75755, 75756, 80874, 80875, 
    80894, 80895, 80896, 80897, 80898, 
    80899, 80900, 80901, 80902, 80903, 
    80921, 80923, 80924, 80922, 80929, 
    80934, 80935, 82751, 82752, 82753, 
    82754, 82755, 82756, 84224, 84225, 
    84226, 87236, 87239, 87237, 87241, 
    87240, 87238, 87242, 87243, 87244, 
    87245, 87246, 87262, 87263, 87467, 
    87466, 87465, 87470, 87469, 87468, 
    87251, 87249, 87662, 87661, 87663, 
    87664
  )

Query time 0.00330

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 (75757,75754,75755,75756,80874,80875,80894,80895,80896,80897,80898,80899,80900,80901,80902,80903,80921,80923,80924,80922,80929,80934,80935,82751,82752,82753,82754,82755,82756,84224,84225,84226,87236,87239,87237,87241,87240,87238,87242,87243,87244,87245,87246,87262,87263,87467,87466,87465,87470,87469,87468,87251,87249,87662,87661,87663,87664)"
        }
      },
      {
        "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 = 'vi'"
        }
      }
    ]
  }
}