SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af5032c57a6976d7831e99d16ef55408f500362b8202a19faadfe2bdd8b274aa' 
  AND token = 'SYOPe9wOiXtelwqsWUMTnD7Yw+Byu4bbqmWUwUW0Xtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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