SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b4840bb099a0492905ff20658a515871e4f025d6564d4743dfc44b594241569' 
  AND token = 'n59/Oej2wyPVKnzmJ/T1QBXT1JYWbQ28MhYIi/JuX8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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