SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9b9826051180d353e918e75b41891e396c747a821296235f7ba2e5b59e1039f' 
  AND token = 'TivE3eNnNAEqrhglx7531tPIzaSq/1lGwafCAxZLzfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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