SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d628e83f0e2bb27f5b06fc97b7d85b99c9b44036d19ff8e3780ffb253d814b' 
  AND token = 'dLsfBt3uiu+MiehcVzn4utcgIgq+hRUFpcqYTs//8no=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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