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 (
    68123, 68124, 68122, 68602, 68603, 68786, 
    70249, 70248, 70247, 70246, 70245, 
    70244, 70243, 70242, 70241, 71341, 
    71339, 71338, 71337, 71336, 71335, 
    71334, 71333, 71332, 71331, 71342, 
    73924, 73923, 74799, 74800, 74803, 
    74804, 76705, 76704, 76703, 76706, 
    79318, 79319, 81689, 81690, 81691, 
    81705, 81706, 85980, 85981, 86219, 
    86218, 86220, 86592, 86593, 86594, 
    86595, 87021, 87022, 87023, 87341, 
    87342, 87343, 87344, 87345, 87337, 
    87340, 87339, 87338, 87336, 87335, 
    84152, 87604, 84154, 87603, 87602, 
    87601, 84156, 84153, 72793, 72792, 
    87350, 87711, 87712, 87713
  )

Query time 0.00838

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": 80,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68123,68124,68122,68602,68603,68786,70249,70248,70247,70246,70245,70244,70243,70242,70241,71341,71339,71338,71337,71336,71335,71334,71333,71332,71331,71342,73924,73923,74799,74800,74803,74804,76705,76704,76703,76706,79318,79319,81689,81690,81691,81705,81706,85980,85981,86219,86218,86220,86592,86593,86594,86595,87021,87022,87023,87341,87342,87343,87344,87345,87337,87340,87339,87338,87336,87335,84152,87604,84154,87603,87602,87601,84156,84153,72793,72792,87350,87711,87712,87713)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}