SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '455783bd002dc1847d4a5490714651f370a20f9e2a4fb7b4cdfaf0393a52f934' 
  AND token = 'ml8PhMwY/FigXyHW57hCEmuhzuVeilWI7CNdG+CXsJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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