SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c593dffbe1591a3dc46a1e72dae0d6d43945aebb2d519b7384246c2ba640ac' 
  AND token = '/gnAqRvkGpp64XmcacbJUihJTDdg7M7ChBL0azStdJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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