SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57ad99600b966d0d0c51cd319c3345f5dbcb8d6646ed878f66428d42fcbd8f9b' 
  AND token = 'gPIJMlFiVp22KrvXqTIxjVv/VDBA6/+L9pLc6oZ4rT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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