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 (
    72838, 72837, 72836, 72835, 72834, 72833, 
    72839, 72848, 72849, 72885, 72884, 
    72883, 72882, 72881, 72880, 72879, 
    72878, 72877, 72886, 82683, 82682, 
    82681, 82685, 82684, 82686
  )

Query time 0.00873

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": 25,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (72838,72837,72836,72835,72834,72833,72839,72848,72849,72885,72884,72883,72882,72881,72880,72879,72878,72877,72886,82683,82682,82681,82685,82684,82686)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}