SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81dbaa4c577d854df2e8a5fb988b390ba4e4f2ad28cb5297446a83997f228a03' 
  AND token = 'Roa7tUN8BIFTCsMF1KtuE0fxvcMZNdMp/XoeP7CxcPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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