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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd92a8017f181be8d879b58f9c8d9c464de936f5d628adedb752d2dc36fead17f' 
  AND token = 'umTVs2uzRSG/eneJhdt0ElX7tOO6I66l/BXeEzb65A4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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