SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a802f7d4d67bee20acea2211a0f6934fe9a3b1e142d86ac92f423dd32a3be5b' 
  AND token = '8Kx5+CHvW9VibSZxcYBgggvrsCBTxYl/OBXY15Sghks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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