SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbd8858df56b8961207ed0c0659c003945a4e51d5993c56d9bd612d85f65e96c' 
  AND token = '53nJsMOByHh7CUO/XgV+pCbHzcGInOesqpsdgFleECw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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