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 (
    70905, 70904, 70903, 70906, 75974, 75969, 
    75970, 75971, 75972, 75973, 78147, 
    78145, 78146, 79251, 79252, 81655, 
    81656, 81660, 81661, 81662, 85749, 
    85757, 85758, 85759, 85750, 85751, 
    85752, 85753, 85754, 85755, 85756, 
    85875, 85874, 85873, 85872, 85876, 
    85877, 85878, 85879, 85880, 85881, 
    85882, 85864, 85865, 85866, 85867, 
    85868, 85869, 85870, 85871, 86261, 
    86260, 86259, 86258, 86257, 86256, 
    86333, 86332, 86331, 86335, 86334, 
    86716, 86717, 86718, 86719, 86720, 
    86721, 86722, 86723, 86724, 87456, 
    87455
  )

Query time 0.00696

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": 72,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70905,70904,70903,70906,75974,75969,75970,75971,75972,75973,78147,78145,78146,79251,79252,81655,81656,81660,81661,81662,85749,85757,85758,85759,85750,85751,85752,85753,85754,85755,85756,85875,85874,85873,85872,85876,85877,85878,85879,85880,85881,85882,85864,85865,85866,85867,85868,85869,85870,85871,86261,86260,86259,86258,86257,86256,86333,86332,86331,86335,86334,86716,86717,86718,86719,86720,86721,86722,86723,86724,87456,87455)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}