SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20778a863c8928e55bfb18582ffecf9af88378de998c1f51aa463a901d6cb16c' 
  AND token = 'sXdDRUUcPtq503787hejJjrIy5sCFA/N1PpnFzDPnVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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