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 = 'en' 
WHERE 
  pfv.variant_id IN (
    79876, 79877, 79878, 79879, 79880, 79881, 
    79883, 79884, 79882, 79892, 79891, 
    79890, 79889, 79894, 79893, 79896, 
    79895, 79898, 79897, 79902, 79901, 
    79899, 79900, 79906, 79905, 79904, 
    79903, 79908, 79907
  )

Query time 0.00106

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": 29,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (79876,79877,79878,79879,79880,79881,79883,79884,79882,79892,79891,79890,79889,79894,79893,79896,79895,79898,79897,79902,79901,79899,79900,79906,79905,79904,79903,79908,79907)"
        }
      },
      {
        "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 = 'en'"
        }
      }
    ]
  }
}