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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '15d0d6cea5ba2e3a3adea767a153a5e7ee79e74ae37a961e5b204b4c8a9e06a7' 
  AND token = 'Vk9TkjH12C26lrqpMd1oq3MH37mFhnzldT7zmZnps5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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