SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '492835229732f55a4491fcf94691fa6452561f41e3b03e460a3eb2d76bd0ea9e' 
  AND token = 'sGeti+w11znErxLh/Pv0EvFT8KkUYWVVBBGrYUrxEgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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