SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc78d5a29725e551f93e6f5217373157d2903695427d24da530ac826e5782485' 
  AND token = 'mvS17dHubtRhRXs01D7bHdejAj0vK/QWlJl0Gwikd2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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