SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '15f85f3e09594c62ca1c773ee74c3c1fc3629ac5bc0a3f8b7e5348c8769141f1' 
  AND token = 'CVwjZHwRaKcbhjdoWB1FhUyZQ/AlzPEtV3zjWG37Zn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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