SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '534b0bf7496e9741836e4920a856f72f71ba88b57fb84196eaa7aaa09e4b2fb1' 
  AND token = 'IVTVslFBElQ/VZfGb96xFwj3Gd37w+v6aZ+6+fCuxbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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