SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81431986d8e6987eac564202e0d8962d48fc7af68266fb29a4eed5cb1826bee1' 
  AND token = 'GgjKqcBvqpsecQVZzilrK8bTodlSmLrWjtoJ1olt5+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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