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 (
    70938, 70937, 70939, 70971, 70970, 70972, 
    74429, 77472, 77917, 82351, 82352, 
    82353, 82354, 82355, 82356, 82381, 
    82382, 83944, 83945, 83959, 83954, 
    83963, 83955, 83956, 83957, 83958, 
    83961, 83960, 83962, 83973, 83972, 
    83971, 83975, 83983, 83974, 83977, 
    83980, 83978, 83981, 83982, 83979, 
    83976, 85457, 85458, 85459, 85460, 
    85461, 85462, 85989, 85988, 85987, 
    85986, 85985, 85984, 86391, 86392, 
    86393, 86394, 86395, 86396, 86397, 
    86398, 86403, 86404, 86405, 86402, 
    86401, 86406, 86407, 86493, 86492, 
    87176, 87175
  )

Query time 0.00296

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": 73,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70938,70937,70939,70971,70970,70972,74429,77472,77917,82351,82352,82353,82354,82355,82356,82381,82382,83944,83945,83959,83954,83963,83955,83956,83957,83958,83961,83960,83962,83973,83972,83971,83975,83983,83974,83977,83980,83978,83981,83982,83979,83976,85457,85458,85459,85460,85461,85462,85989,85988,85987,85986,85985,85984,86391,86392,86393,86394,86395,86396,86397,86398,86403,86404,86405,86402,86401,86406,86407,86493,86492,87176,87175)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}