SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bf1d98cd0f48f037de4e968a279e283c9714d17506deee06f861f72085eaceb' 
  AND token = '3PuQfeDD2sua/TVHwF9rXoTuNyCGW2VLtvQq1SmreI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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