SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'debe9bf0c172ae287a7c93b1a44aeae60e5cd68f93233057059f126c98591780' 
  AND token = 'sQdhOYp0UxOSpgqBVJGtRiKEqMqGlTLMKartjg9lWeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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