SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d151da9cd0535895a823fc53b11bc711e2fe9739b83661cf57ad45cf312e75f' 
  AND token = 'VXwo0PUyzzK+JHRPxvUYeN3+ggKXclwyibXCLFkD8g0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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