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 (
    68747, 68746, 68745, 68744, 68743, 68748, 
    71071, 71072, 71553, 71552, 71557, 
    71556, 74110, 74109, 74646, 74657, 
    74656, 74655, 74654, 74653, 74652, 
    75729, 75736, 75730, 75731, 75732, 
    75733, 75734, 75735, 77111, 77110, 
    79199, 79198, 79927, 79926, 79925, 
    81505, 81506, 81507, 81508, 85306, 
    85307, 85308, 85305, 85318, 85319, 
    85317, 85327, 85326, 85635, 85629, 
    85634, 85626, 85636, 85627, 85628, 
    85633, 85632, 85631, 85630, 85738, 
    85746, 85747, 85748, 85739, 85740, 
    85741, 85742, 85743, 85744, 85745, 
    85749, 85757, 85758, 85759, 85750, 
    85751, 85752, 85753, 85754, 85755, 
    85756, 86656, 86657, 86658, 86659, 
    86660, 86661, 86662, 86882, 86883
  )

Query time 0.01281

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": 91,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68747,68746,68745,68744,68743,68748,71071,71072,71553,71552,71557,71556,74110,74109,74646,74657,74656,74655,74654,74653,74652,75729,75736,75730,75731,75732,75733,75734,75735,77111,77110,79199,79198,79927,79926,79925,81505,81506,81507,81508,85306,85307,85308,85305,85318,85319,85317,85327,85326,85635,85629,85634,85626,85636,85627,85628,85633,85632,85631,85630,85738,85746,85747,85748,85739,85740,85741,85742,85743,85744,85745,85749,85757,85758,85759,85750,85751,85752,85753,85754,85755,85756,86656,86657,86658,86659,86660,86661,86662,86882,86883)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}