SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '78e392a93edebd396bc231e24d02602526ff0913b291def55a46f3b6d0b19602' 
  AND token = 'cBqCAgitnhX5P6Hor3EbVg3IjM8qjh09XVob0aUlhGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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