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 (
    68977, 68976, 68975, 68978, 68974, 68994, 
    68993, 68992, 68991, 68990, 68989, 
    68988, 68987, 68995, 68986, 69030, 
    69029, 69028, 69027, 69026, 69025, 
    69024, 69023, 69031, 69022, 69038, 
    69037, 69036, 69035, 69034, 69033, 
    69039, 69032, 69858, 69857, 69856, 
    69855, 69854, 69859, 69864, 69863, 
    69862, 69861, 69860, 69865, 69876, 
    69875, 69874, 69873, 69872, 69877, 
    69882, 69881, 69880, 69879, 69878, 
    69883, 70010, 70009, 70008, 70011, 
    70007, 70028, 70027, 70026, 70025, 
    70024, 70029, 70033, 70032, 70031, 
    70030, 70034, 70051, 70050, 70049, 
    70048, 70052, 70047, 70064, 70063, 
    70062, 70061, 70060, 70065, 70059, 
    70077, 70076, 70075, 70078, 70074, 
    70088, 70089, 70087, 70094, 70093, 
    70092, 70091, 70095, 70090, 70991, 
    70992, 71005, 71004, 71003, 71002, 
    71001, 71006, 71013, 71012, 71011, 
    71014, 71015, 71016, 81927, 81928, 
    81929
  )

Query time 0.00847

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": 117,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68977,68976,68975,68978,68974,68994,68993,68992,68991,68990,68989,68988,68987,68995,68986,69030,69029,69028,69027,69026,69025,69024,69023,69031,69022,69038,69037,69036,69035,69034,69033,69039,69032,69858,69857,69856,69855,69854,69859,69864,69863,69862,69861,69860,69865,69876,69875,69874,69873,69872,69877,69882,69881,69880,69879,69878,69883,70010,70009,70008,70011,70007,70028,70027,70026,70025,70024,70029,70033,70032,70031,70030,70034,70051,70050,70049,70048,70052,70047,70064,70063,70062,70061,70060,70065,70059,70077,70076,70075,70078,70074,70088,70089,70087,70094,70093,70092,70091,70095,70090,70991,70992,71005,71004,71003,71002,71001,71006,71013,71012,71011,71014,71015,71016,81927,81928,81929)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}