SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ef651a33e8272c973460d29a30ade940f5b4ef04cc4544b9eecf5006fa85737' 
  AND token = 'f0H3YCgbKuqhmRhqRauYKOVjd1WLsv7TtVNrI+iMvHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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