SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5596ddd752847da7820f164d7803f9bbc5008d2ef2b066546931579cb0845a51' 
  AND token = 'Su4DQNL4rT1QzbOz/vIBrYRiUhGJ/S5IpZg7LnlAy14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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