SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '003a53a7314ed64a1a2a7f05e7f896746e9f704c82c7489235763beff5738c4f' 
  AND token = 'lBZa/UCzPpr7BELUeGUVvkb2TJomFOmbsCZZ+A1QbGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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