SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b20ada2f8b7c9ef2aa3a27e91523464f9efb98e223d52fc78525f182697d4341' 
  AND token = 'sB/wi7BG2/UAyzIJPVfi0WXYOz5KDBH4h97TpxvVMAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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