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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5324fdfdcd9902dec1a8a60c6ddb325139691eb391f50360728bf6e7aaddbdf4' 
  AND token = '4WcxSKhkrdH13VJk4+/Fm6EgZkO1Dv7ypi/DmSt2O7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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