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 (
    70572, 70571, 70573, 70687, 70686, 70685, 
    70684, 70683, 70694, 70693, 70692, 
    70691, 70690, 73494, 73495, 76693, 
    76691, 76690, 76692, 80874, 80875, 
    81481, 81482, 81483, 81484, 81991, 
    81992, 81993, 82372, 82373, 82374, 
    82375, 85990, 85999, 86000, 86001, 
    86002, 86003, 86004, 86005, 86006, 
    86007, 86008, 86009, 85991, 85992, 
    85993, 85994, 85995, 85996, 85997, 
    85998, 86589, 86585, 86588, 86586, 
    86587
  )

Query time 0.01013

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": 57,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70572,70571,70573,70687,70686,70685,70684,70683,70694,70693,70692,70691,70690,73494,73495,76693,76691,76690,76692,80874,80875,81481,81482,81483,81484,81991,81992,81993,82372,82373,82374,82375,85990,85999,86000,86001,86002,86003,86004,86005,86006,86007,86008,86009,85991,85992,85993,85994,85995,85996,85997,85998,86589,86585,86588,86586,86587)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}