SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '514b61b69048601bd35417914c577b6728cfe678174513d442db666e595cfb67' 
  AND token = 'pasNBDl0D2tKrLbmLpeuQOIPhEKAjdbFk6x40MLKCJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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