SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5ad83f48ac053fa801f0e16adb5387e7f103edfeacf1da51071643505071f46' 
  AND token = 'O9KZttY5MqbCpBNeEy6fIWN6fQmWqdtFlrUC/Hp+HNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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