SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '19b40c88818d48c3f9519aee800f4e3ac1574cf85572bbb17aaec0af99ca6ae3' 
  AND token = 'ZWvUrdZRq7wFH0JQRFKMcW5f5lGKyaE024j2YKapEww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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