SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdcdce5e17d248c703832b022a9364607f8cf8a18d3a60afe923027589649b37' 
  AND token = 'zx+ZESPncEPOGLXdUz8QYhi5zBZuq3SJ5n/KJAchIlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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