SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '102343b9c2d510f3cbb291a50064e44a3bb58fd80ebd698af057b1db4b0b4e11' 
  AND token = 'es0ZwfTapxLlcFJVu3XRayJtbtgWTScvvjbzvBqSkBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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