SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ac0302f57c50258b4befad015da682e53dced4051e66917cafb3738e39f01f' 
  AND token = 'T2MR9SYshLYyF/+jUPoXGOftjxJOFTEE62M0Ogbdcjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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