SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4878bfdd4552cd0162dffc040fb9e77b560bad49395964fc52b26f767366cb57' 
  AND token = 'sp8EZ+/mByPLHcSEmj9JYXqItNSbyM49HyOHGf25LJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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