SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0d3651e28131a0e5bededf003219753483813db88908ba506096ab596f85fcdb' 
  AND token = 'QjPrk9hiNoulVKzh4PUTgtHlD//FTzBl1x+2AJm+SR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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