SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc509cb10722d664ca1ff3e8bbd445f5c124f3438ebd43cb4ac44ab7603c40d2' 
  AND token = 'mhuNmekpLQ0HBqBOTDIU/NEg5Vti+wwRnr8C1v0NkG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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