SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ae8b9854a9487bb7e5671f73e2f1d9c99a076f8a98334ac41459ff62ddb7c5f' 
  AND token = 'Xz2cstw+GamcSJk+3nnkxDBhOKQRYyIDReFjGz3OiD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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