SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '927b87a2062bf019a95db7344267b9e4845bbc6393d244c7c27d3549539d12d8' 
  AND token = '9FV8D7LeNw+t0GoY0F6pcD0vlju+tXn/pRUjq/bTzqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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