SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcf8bcba171494e235248881466d9d6ef9bf206755ce6012f263acb4f08a89ac' 
  AND token = 'pXiJfpTGMDrKdAkmPQZTPl6wM7SUS0R55wn2gD3xjwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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