SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c354953e3e1b2bb7c539c8771f2b534dc47d502cc821ac1f87624b7c4384ec8' 
  AND token = 'GNbFQl3OVQOFti+LzRJ1STDcs++F8yXqHJR2NB3sptM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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