SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21981447f3dd92cd18a972d672dbea3b37835e4ea7e1f1b03cf16331bcb792bb' 
  AND token = 'EW5JMBsesQePDnv4f61v5wbsrqMSnkDy/zlkSA9q5Ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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