SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0af6472dc5f26579151804c61c93fd8935ac6794139586ab72b0d24ee55f309' 
  AND token = 'xg465hgmzScSK4MvH+fFBulOSXVFq5kh0RP8A17MVJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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