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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9ddb568716530839a3a50d8ad655665bec6d871d9f8ba59f0f9e3ac3a4cdccb4' 
  AND token = 'WmZ6R2wn/YlHbqq5j76dllI5TFUJe1lNTUcfeBosXAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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