SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5456a4f374ffd0999fb2bf2dcf21d4d13b017c9b946294f7ef7bccdaf2b47bee' 
  AND token = 'ku9nJwgFAqPmKP6WtRpqq3YPTRIgo/HNahgVQ05XuIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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