SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85e1cbb4208c1d27e4e3e44e31515e8e4fb90774204fedec6038b2d5bd8fe56d' 
  AND token = 'dz2MxduzZ9AqapqJFF+ZQOCpAgwFJiRDtUlmS0C+Qfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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