SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fca79d05dd9e642ad6443e989d0340628fdda322071c75f9e8a7a61b7cdd3c9b' 
  AND token = 'Scm37uclq595jUTp7BSVvLBnDWPUVKkzFNraranxGUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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