SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8188b274b01087a0d1ac50a13b09218d27a43ed8054a7b16cef03ab28a553f4' 
  AND token = 'IEWb3V/EjJlbyAfkUPMeanruEk/lg8WpGFFtWyIrSG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}