SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '392f7db4ee5d62d4684d2579a25bd617acf0abce1b3fa5ca802a5d8ad2ab33aa' 
  AND token = 'p9n9GhOIRo5aFgz8YwTHfurlYzkbfiVkKGN/gYK+G+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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