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 (
    86161, 86160, 86159, 86169, 86173, 86171, 
    86170, 86168, 86176, 86172, 86177, 
    86174, 86175, 86197, 86189, 86196, 
    86195, 86194, 86193, 86192, 86191, 
    86190, 86188
  )

Query time 0.00096

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": 23,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (86161,86160,86159,86169,86173,86171,86170,86168,86176,86172,86177,86174,86175,86197,86189,86196,86195,86194,86193,86192,86191,86190,86188)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}