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 (
    68322, 68323, 70114, 70115, 71071, 71072, 
    71563, 71564, 71562, 71567, 71568, 
    71825, 71824, 71823, 71826, 72227, 
    72226, 72224, 72223, 73432, 73433, 
    73431, 73451, 73450, 73449, 73489, 
    73488, 74807, 74808, 75522, 75521, 
    75960, 75961, 75962, 75963, 75964, 
    75965, 75966, 75967, 76618, 76617, 
    76738, 76737, 76739, 81888, 81892, 
    81893, 81894, 81895, 81896, 81897, 
    81889, 81890, 81891, 84334, 84333, 
    84332, 84331, 84330, 84329, 86218, 
    86219, 86220
  )

Query time 0.00394

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": 63,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68322,68323,70114,70115,71071,71072,71563,71564,71562,71567,71568,71825,71824,71823,71826,72227,72226,72224,72223,73432,73433,73431,73451,73450,73449,73489,73488,74807,74808,75522,75521,75960,75961,75962,75963,75964,75965,75966,75967,76618,76617,76738,76737,76739,81888,81892,81893,81894,81895,81896,81897,81889,81890,81891,84334,84333,84332,84331,84330,84329,86218,86219,86220)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}