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 (
    70876, 70877, 71009, 71008, 71007, 71010, 
    74805, 74806, 81269, 81270, 81685, 
    81686, 81917, 81922, 81923, 81924, 
    81925, 81926, 81918, 81919, 81920, 
    81921, 85255, 85256, 85257, 86590, 
    86591, 86606, 86607, 86608, 86706, 
    86711, 86712, 86713, 86714, 86715, 
    86707, 86708, 86709, 86710, 87124
  )

Query time 0.01240

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": 41,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70876,70877,71009,71008,71007,71010,74805,74806,81269,81270,81685,81686,81917,81922,81923,81924,81925,81926,81918,81919,81920,81921,85255,85256,85257,86590,86591,86606,86607,86608,86706,86711,86712,86713,86714,86715,86707,86708,86709,86710,87124)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}