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 = 'uk' 
WHERE 
  pfv.variant_id IN (
    3096, 3084, 3095, 4983, 3089, 4974, 4979, 
    3103, 3093, 3098, 3099, 3104, 4981, 
    5138, 3094, 3097, 4913, 3686, 3092, 
    4922, 3101, 4980, 3100
  )

Query time 0.00071

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": 23,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (3096,3084,3095,4983,3089,4974,4979,3103,3093,3098,3099,3104,4981,5138,3094,3097,4913,3686,3092,4922,3101,4980,3100)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["lillyshop_lillyshop.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'uk'"
        }
      }
    ]
  }
}