SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1536909beb146bc55df617217ab00a57bbd372ba7fa027515e73327988d287cc' 
  AND token = 'JW+ObzXs3V4GsdDi/X/mLhLq1tbx7fxFmhzZDzaP+b4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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