SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ef815a5a3f00986f95af5d640ca2bcc7f9af2c628ac1ca23f6e9c507bc9830' 
  AND token = 'cmbzUx1fqWl+aV9+PIgW4yHjDK25t25zCayOTEKCCaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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