SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36c7edcf58084cfd61288a8d44b2fbec117fec9bf34afb60f368c9d3bf030421' 
  AND token = 'dcTrGp8FvUmYlQWowvE2qQFt8tIp0dsBADGoWGDfH6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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