SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9beaca70de521ad515ce929283e6e8c421d059e79d301b04ab744546c43bafb6' 
  AND token = 'R2+pvPFAwtZjBLXOLf4PVA/QT0LK7GuZljh7Y0WA68k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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