SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9deb1f518be6a64707d80c26077d67baa803cfb138c89fb7c7f1a585311dc1d2' 
  AND token = 'nnAowcHHGBd9DYxR4FK0RvbFThGTVKJLQEq9IRqaMFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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