SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '159c5c0cf09ea2fd7879ceb75ac727e08f6ce6f5b3288b7a7c884491ad521b50' 
  AND token = 'd+gKwpNDsVzKMNGlWMWUxR+IFlYpYzBBn0thL/A0tn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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