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 (
    86930, 86931, 86932, 86933, 86938, 86939, 
    86940, 86941, 86950, 86951, 86952, 
    86953, 86962, 86963, 86964, 86965, 
    86966, 86967, 86968, 86969, 86998, 
    86999, 87000, 87001
  )

Query time 0.00141

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": 24,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (86930,86931,86932,86933,86938,86939,86940,86941,86950,86951,86952,86953,86962,86963,86964,86965,86966,86967,86968,86969,86998,86999,87000,87001)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}