SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b01b64744e06222753c1912106aa4d68b8d5efc3fc1a5476a5a43507b8dbcb3' 
  AND token = '5Qq8Lv+dYSvfgKHYDvq9eJAzzGet0iQ+hIGp9hHVFLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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