SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0af7847c5d8d92331aaf099d6be42442d9dda7f5f67811bffcda63e22916a2b2' 
  AND token = 'GFkV5DKc+LPErP45ZxRi9Wq2HYoFhKWxIDmM/aK9iGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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