SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18d5588e6462c796e43f6f8e62a74659f261d934d1b65750ee72ea62c2d35983' 
  AND token = 'ZG+OFn+vv6PxbASujGFKAUXm2WMpa4+g/eV2BFMNsM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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