SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e3856c961fd903c6082729261b99fbcfe22381e610bdfc33c4f9cc6bee3eb84' 
  AND token = 'v6S6wTY9vYOFZ7KlGjvp4CwrJXMoLZKkQQQYd3E0X0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}