SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed8527d7de98080ca191c49acec7c593b8731467b0d20942faf1ddcfbeaa9055' 
  AND token = 'OiXjQdALzz2SemmoAjqCi3dhMqH2h0LuBWq25khQqH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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