SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dff578f2e97f425381be8ff46258902be2b0065a05dea3294010aab76edbcbd' 
  AND token = 'C+IxrXaPPDqCAJrGB904UZFKbQ6xoFx2zkzfn8TqyW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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