SELECT 
  variant_id, 
  yml2_unit 
FROM 
  cscart_product_feature_variant_descriptions 
WHERE 
  variant_id IN (
    '1892', '1855', '2470', '1930', '1580', 
    '129', '1856', '1870', 'Y', '1353', 
    '486', '489', '1448', '43', '895', 
    '356', '1020', '214', '44', '1451', 
    '136', '121', '710', '45', '490', '46'
  ) 
  AND lang_code = 'uk'

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_feature_variant_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "rows": 26,
          "filtered": 100,
          "index_condition": "cscart_product_feature_variant_descriptions.variant_id in ('1892','1855','2470','1930','1580','129','1856','1870','Y','1353','486','489','1448','43','895','356','1020','214','44','1451','136','121','710','45','490','46') and cscart_product_feature_variant_descriptions.lang_code = 'uk'"
        }
      }
    ]
  }
}