SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e441d73ffa83e041f5447134f18b1370f3c3c0db0a3069b8da7adf90a33b4dd' 
  AND token = 'g48bPk+JfQmrFVLdNUoFC/uMzHGCJXLQ4n/NZI/y/fM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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