SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6a5c6afaa81e0149993a20051146eb966053fc6dcb2a4f0256d967ccbdd83f4' 
  AND token = '8qHkbWBKqEMLCX5tNWuow33p/yqb2rs+UTvMfcczxsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}