SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a40a3e345d52928c24eef5e058604d572cd039e1a587d44e585a485da75f1b4' 
  AND token = 'X9n2D8ywP25N32F1652eqtjLsM+ArFSPd8zj2D6XCW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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