SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdf5a64218f2eb006f71eeca78448c782bd7a8197da8a9580c806e908441aec6' 
  AND token = 'YuXppl47QA5YjGdBooStQQWUFHZlXMTgrCZbHlOnVF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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