SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f2e42828d0f8a1a5469855d14c69f8663a36d0471679e0de4d50d0e5f88c77' 
  AND token = 'jjRcNNDID+6yLIAhn5mOv6Wvvz+udJdzy1fjFENHD70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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