SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759f479e1c8fe0141a8dac30f59b9a67431b5780e1f34bf390da575a71f070eb' 
  AND token = 'sqUGum5JFRGOpzpGYZwETlvVjszeqq8WDyuur69ByLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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