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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '53e260ce0ec3ebe9eb44d76be22ba1eb326dc43bb660eadaf90a33d813bed0ff' 
  AND token = 'a2n1Cm/65WaNnihIoWLFtiJzVLS0rgcVLnGe+e102MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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