SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75014cd47ba33bedc073414d14fdf1203e8300e9211cfff93f7921aaf31af5a1' 
  AND token = 'Cgy+8dSkP6S/tyO7H3oISOB0+uZnJ73KzEIKZWVhGh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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