SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ac29415166f04fa36d24be9653716c952130b650f7382490463511a41e2b145' 
  AND token = 'y5oDurXKLPHEPQ1rDCsq1WOqxJVvBiZHhtSskyPy91E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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