SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c0731d9f0929053d6adc9751702ac5a39a5b976b7969d3dd288091024d0c267' 
  AND token = 'FZ61Zp+3aT1206LQiw3tLwv1NRkuSzMhpqqsym9XwZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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