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 (
    69835, 69836, 69840, 69839, 69841, 69845, 
    69844, 69843, 69842, 69846, 69850, 
    69851, 71079, 71080, 75757, 75754, 
    75755, 75756, 77369, 77370, 77372, 
    80874, 80875, 80898, 80899, 80900, 
    80901, 80902, 80903, 80929, 80934, 
    80935, 82738, 82744, 82747, 82748, 
    82749, 82750, 82739, 82740, 82741, 
    82742, 82743, 82745, 82746, 82751, 
    82752, 82753, 82754, 82755, 82756
  )

Query time 0.01342

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": 51,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (69835,69836,69840,69839,69841,69845,69844,69843,69842,69846,69850,69851,71079,71080,75757,75754,75755,75756,77369,77370,77372,80874,80875,80898,80899,80900,80901,80902,80903,80929,80934,80935,82738,82744,82747,82748,82749,82750,82739,82740,82741,82742,82743,82745,82746,82751,82752,82753,82754,82755,82756)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}