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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7851a17365e1d8f200edb723e80c27bf4cb55a2cdf01bf050d5ff8fae994eb17' 
  AND token = 'Q95bgiKZlwSKyCOtKS6VgpHz7claqz8EcL9AdI1kz/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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