SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a815bbdf0d99b749d48b2cf96ba3536ffc46b2ed658a77a5deb002ff6218283' 
  AND token = 'S3hGwOJ6P6Oz+WwJS70/RwY6wfgMqZVv4T78LkwVWTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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