SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf253ec95952dfbb37ed5ee2ec50f3c6c148b7e4b6572a808e5fe5c115195244' 
  AND token = 'f91MvNMXK7iQW4fMrwxczbJ4Ll5EFEgTk9AqAqzj/hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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