SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a28cd6a6cd308cc7e4b7853f88302c750b2212dfb52de284848b9e55d50c29d' 
  AND token = 'xMc5B2JKfVcJmzMxMeBLJVEzcLRayjfoNkfn60CPmD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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