SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c6baa31d37399cf46b4166526f99823d64a467ac03c762cef0091e991a27f6' 
  AND token = 'VhnCdGglLvWe85GTFlw7NvbTUXZEq8tyHu+cRYP9z6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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