SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c5a5ed5a094534d2488f8a976813b96958f93790f3f450f1ffcf5af4b9361d4' 
  AND token = 'rtjmAvfS6ZZNUJamIhNwZgWXcNpTEOUA2HawbMnnZdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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