SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f39866d76d85b29252056453fffef0d3317139d63a8c4733bae55277244910' 
  AND token = 'OqJKzSZsWCH7TeRX3K/o3v6rzYL5ZTbb9sL1gPDOXrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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