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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6a9dcbb0339fc32d328e0f6ab17d77aff20c0c13750b655c6d52cd34f5d6bc5e' 
  AND token = 'QBA969bCuugWpVT/1fpvfdNFu3zUuksvK/2gmiBINyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}