SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2e2e2b9d280862de3d13a6ecf5390c1f828d08ac7fce8702aa96dd6fc505416' 
  AND token = '9mrGA/2nB/MRFcRgVoOxliCMy7WHZ9+Zpz6tjDYQjlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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