SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d761e83e5672e9784e7accded8ca6c121b44445e0a66c0ca1154d2f2311ee5d' 
  AND token = 'e1wmclpz9RkMivKXuRfvBsxVVC4HyvqouYcj9kWtVO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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