SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c92d7426ab16d8535b48423162b5ad104bebb4dfe3d0197ea183caec548677e3' 
  AND token = 'ytnifNGsCVm5sdhrOWqJo7vV+UOOHtIxfMpiCHOhVLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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